Thin film deposition method and atmospheric pressure plasma deposition apparatus

Abstract

The present invention addresses the problem of providing a film-forming method and an atmospheric pressure plasma film-forming device with which it is possible to form a highly flat film at a high film formation speed by atmospheric pressure plasma film formation. The problem is solved by introducing a plasma generation gas from an inside channel passing between an electrode pair, introducing a raw material gas from at least one of a first outside channel and a second outside channel passing the outside of the electrode pair, and having the gas flow rate between the outlet of the first outside channel and a substrate and the gas flow rate between the outlet of the second outside channel and the substrate be unequal.

Description

Technical Field

[0001] The present invention relates to a film-forming method using atmospheric pressure plasma and an atmospheric pressure plasma film-forming apparatus for carrying out this film-forming method.

Background Art

[0002] Atmospheric pressure plasma film formation is known, in which plasma is generated under atmospheric pressure (near atmospheric pressure) to activate a source gas, and a film is formed on a substrate with active species of the source gas. Since this atmospheric pressure plasma film formation is under atmospheric pressure, it has the advantage that an expensive vacuum vessel such as a vacuum chamber is not required, and the equipment cost can be reduced. It also has the advantage that it is possible to process substrates that are difficult to process under vacuum.

[0003] In atmospheric pressure plasma film formation, a plasma generation gas such as an inert gas is introduced between electrodes to generate plasma, and a source gas containing a film-forming material is activated by this plasma. In atmospheric pressure plasma, the active species of the film-forming material thus obtained are attached to the substrate to form a film. Here, in atmospheric pressure plasma film formation, in order to suppress the adhesion of the film-forming material to the electrodes, the source gas and the plasma generation gas are introduced separately, and the plasma generated between the electrode pair is brought into contact with and mixed with the source gas outside the electrode pair to form a film. This method is generally referred to as the 'remote diffusion mixing method' of atmospheric pressure plasma.

[0004] In the atmospheric pressure plasma film formation by the remote diffusion mixing method, usually, the plasma generation gas is introduced through an inner flow path between the electrode pair, and the source gas is introduced from an outer flow path provided so as to sandwich the inner flow path outside the electrode pair, so that the plasma and the source gas are mixed in a mixing portion between the electrode pair and the substrate. For example, Patent Document 1 describes an atmospheric pressure plasma film deposition apparatus and method comprising an electrode pair, a voltage applying means for applying a voltage between the electrodes, an inert gas supply means for supplying an inert gas between the electrodes, and a raw material gas supply means, wherein the substrate (film to be deposited) is positioned downstream of the electrode pair in the direction of flow of the inert gas, the substrate is positioned on a conductor, the raw material gas is supplied outside the electrode pair between the electrode pair and the substrate, and furthermore, the electrode pair is positioned perpendicular to the planar direction of the substrate, and the inert gas is supplied between the electrode pair parallel to the electrode pair.

[0005] In atmospheric pressure plasma film deposition using this remote diffusion mixing method, in order to improve the decomposition of the source gas and increase the film deposition rate, it is preferable to bring the plasma and the source gas into contact for a sufficiently long time in the mixing section between the electrode pair and the substrate to allow for the activation reaction of the source gas. In other words, in atmospheric pressure plasma deposition using a remote diffusion mixing method, it is preferable to increase the residence time of the source gas in the mixing section and thereby increase the mixing reaction time between the plasma and the source gas in order to improve the deposition rate.

[0006] On the other hand, as described in Non-Patent Document 1, in atmospheric pressure plasma film deposition, if the decomposed raw material gas (active species) remains in the gas phase mixing section for a long time, the active species of the raw material gas will aggregate and form fine particles. When such fine particles adhere to the substrate, the flatness of the deposited film is impaired, resulting in a decrease in product quality. Depending on the product being manufactured, it may be necessary to maintain film flatness on the order of a few nanometers in terms of arithmetic mean roughness Ra. Therefore, in this application, it is difficult to increase the film deposition rate while maintaining flatness. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Special Publication No. 2009-506496 [Non-Patent Document 1] Behavior of particulate matter and methods for controlling particulate matter contamination in plasma CVD processes. Yutaka Hayashi, Manabu Shimada, J. Aerosol Res., 21, 3, p.209 (2006) [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] As described above, in conventional atmospheric pressure plasma deposition using remote diffusion mixing, it has been difficult to improve the deposition rate while ensuring the flatness of the deposited film. Therefore, there is a need for a means to realize atmospheric pressure plasma deposition using a remote diffusion mixing method that can deposit high-quality films with high flatness and productivity.

[0009] The object of the present invention is to solve the problems of the prior art and to provide a film deposition method and atmospheric pressure plasma deposition apparatus that can deposit high-quality films with high flatness at a high deposition rate using a remote diffusion mixing atmospheric pressure plasma. [Means for solving the problem]

[0010] To achieve the above-mentioned objectives, the present invention has the following configuration. [1] When forming a film on a substrate using atmospheric pressure plasma, a plasma generation gas is introduced between the electrode pair and the substrate from an inner channel passing through the space between the electrode pair, and a source gas is introduced from at least one of a first outer channel and a second outer channel located outside the space between the electrode pair, A film deposition method characterized by depositing a film on a substrate by making the gas flow rate between the outlet of the first outer channel and the substrate the first gas flow rate, and the gas flow rate between the outlet of the second outer channel and the substrate the second gas flow rate, and making the first gas flow rate and the second gas flow rate uneven. [2] The film formation method according to [1], wherein the raw material gas is introduced from an outer channel corresponding to at least the side with the higher flow rate of the first gas flow rate and the second gas flow rate. [3] The method for forming a film according to [1] or [2], wherein the raw material gas is introduced from both the first outer channel and the second outer channel. [4] A film formation method according to any one of [1] to [3], wherein the amount of gas introduced from the first outer channel and the amount of gas introduced from the second outer channel are different, thereby making the first gas flow rate and the second gas flow rate uneven. [5] A film deposition method according to any one of [1] to [4], wherein the outlet of the first outer channel and the outlet of the second outer channel have different areas, thereby making the first gas flow rate and the second gas flow rate uneven. [6] A film formation method according to any one of [1] to [5], wherein an air supply means is provided on the side opposite to the inner flow path of one of the first outer flow path and the second outer flow path, and air is supplied from the air supply means to make the first gas flow rate and the second gas flow rate uneven. [7] A film formation method according to any one of [1] to [6], wherein an exhaust means is provided on the side opposite to the inner flow path of one of the first outer flow path and the second outer flow path, and gas is exhausted from this exhaust means to make the first gas flow rate and the second gas flow rate uneven. [8] A film formation method according to any one of [1] to [7], wherein the shape of the surface of the electrode that forms the electrode pair facing the substrate is different on the first outer channel side and the second outer channel side, thereby making the first gas flow rate and the second gas flow rate uneven. [9] Electrode pair and, A substrate holding means for holding the substrate, An internal channel introduces gas between the electrode pair and the substrate holding means, passing between the electrode pair and the substrate holding means. A first outer channel and a second outer channel introduce gas between the electrode pair and the substrate holding means, passing outside the space between the electrode pair. An atmospheric pressure plasma film deposition apparatus characterized by having a flow rate control means that makes the gas flow rate between the outlet of the first outer channel and the substrate holding means an uneven gas flow rate, where the gas flow rate between the outlet of the second outer channel and the substrate holding means is called the first gas flow rate, and the gas flow rate between the outlet of the second outer channel and the substrate holding means is called the second gas flow rate. [Effects of the Invention]

[0011] According to the present invention, a highly flat, high-quality film can be deposited at a high deposition rate using atmospheric pressure plasma in a remote diffusion mixing method.

Brief Description of the Drawings

[0012] [Figure 1] FIG. 1 conceptually shows an example of an atmospheric pressure plasma film forming apparatus of the present invention for implementing an example of the film forming method of the present invention. [Figure 2] FIG. 2 is a conceptual diagram for explaining the present invention. [Figure 3] FIG. 3 is a conceptual diagram for explaining the conventional atmospheric pressure plasma film forming of the present invention. [Figure 4] FIG. 4 is a graph for explaining the present invention. [Figure 5] FIG. 5 is a graph showing the measurement result of the gas flow rate in an embodiment of the present invention. [Figure 6] FIG. 6 is a graph showing the result of an embodiment of the present invention. [Figure 7] FIG. 7 is an enlarged view of a part of FIG. 6. [Figure 8] FIG. 8 is a conceptual diagram for explaining the atmospheric pressure plasma film forming of the remote diffusion mixing method.

Modes for Carrying Out the Invention

[0013] Hereinafter, the film forming method and the atmospheric pressure plasma film forming apparatus of the present invention will be described in detail based on the preferred embodiments shown in the accompanying drawings.

[0014] The description of the constituent elements described below is based on the typical embodiments of the present invention, but the present invention is not limited to such embodiments. In this specification, the numerical range represented by "~" means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value. Also, the drawings shown below are all conceptual diagrams for explaining the present invention. Therefore, the sizes, lengths, positional relationships, etc. of the constituent members do not necessarily match the actual objects.

[0015] Figure 1 conceptually shows an example of an atmospheric pressure plasma film deposition apparatus of the present invention, which implements an example of the film deposition method of the present invention. The atmospheric pressure plasma deposition apparatus 10 shown in Figure 1 is an apparatus that deposits a film on a substrate Z using the remote diffusion mixing method atmospheric pressure plasma (atmospheric pressure plasma CVD (Chemical Vapor Deposition)) described above. Therefore, the atmospheric pressure plasma deposition apparatus 10 introduces the source gas and the plasma generation gas separately under atmospheric pressure (or near atmospheric pressure), and the plasma generated between the electrode pair is brought into contact with and mixed with the source gas between the electrode pair and the substrate Z to deposit a film on the substrate Z. Specifically, as conceptually shown in Figure 8, an example of a typical configuration is used in a remote diffusion mixing atmospheric pressure plasma deposition apparatus. In this apparatus, plasma generation gas PG is introduced between the electrode pair 100 to generate plasma, which is then introduced between the electrode pair 100 and the substrate Z. Additionally, raw material gas MG is introduced between the electrode pair and the substrate Z from an external channel 102 located outside the electrode pair 100. This allows the plasma generated between the electrode pair to come into contact with and mix with the raw material gas between the electrode pair and the substrate Z, thereby depositing a film on the substrate Z. In the following explanation, the atmospheric pressure plasma deposition apparatus will also be referred to simply as the deposition apparatus.

[0016] In the present invention, there are no restrictions on the substrate Z (substrate to be coated), and various known substrates that can be coated by atmospheric pressure plasma using a remote diffusion mixing method can be used. Examples include resin films (polymer films, plastic films) made from polymer materials such as polyethylene terephthalate (PET), polyethylene naphthalate, polyethylene, polypropylene, polystyrene, polyamide, polyvinyl chloride, polycarbonate, polyacrylonitrile, polyimide, polyacrylate, and polymethacrylate, as well as silicon substrates.

[0017] Furthermore, there are no restrictions on the film to be deposited on the substrate Z; various known materials that can be deposited by atmospheric pressure plasma deposition using remote diffusion mixing can be used. Examples include gas barrier films made of silicon dioxide, silicon oxynitride, silicon nitride, and aluminum oxide; light-reflective and anti-reflective films made of silicon dioxide, titanium dioxide, zinc oxide, tin oxide, and fluorine compounds; transparent conductive films made of indium tin oxide, tin oxide, indium oxide, zinc oxide, indium cadmium oxide, cadmium tin oxide, cadmium oxide, and gallium oxide; and DLC (Diamond-Like Carbon) films.

[0018] Furthermore, various known raw material gases and plasma generation gases are available, depending on the type of film to be deposited. The raw material gas is a gas containing the components that will form the film, while the plasma generation gas is a gas used to generate plasma. For example, when depositing DLC ​​films, examples include hydrocarbon gases such as methane and acetylene as source gases, and argon as the plasma generation gas. When depositing silicon oxide films, examples include TEOS (tetraethoxysilane) as the source gas and nitrogen as the plasma generation gas.

[0019] The film deposition apparatus 10 shown in Figure 1 comprises a cylindrical electrode 12, a film deposition unit 14, and an AC power supply 16. Note that in Figure 1, the cylindrical electrode 12 and the film deposition unit 14 are shown in cross-sectional view, but hatching has been omitted to simplify the figure and clearly show the configuration of the film deposition apparatus 10. Furthermore, for convenience, in the following explanation, the position of each component will be expressed as top and bottom, and sideways (right and left), as shown in Figure 1. However, these vertical (up and down) and horizontal (sideways) directions do not necessarily correspond to the actual usage state of the film deposition apparatus 10.

[0020] The cylindrical electrode 12 is a cylindrical electrode whose height direction (axial direction) is perpendicular to the plane of the paper in Figure 1. There are no restrictions on the cylindrical electrode 12; various known cylindrical electrodes used in atmospheric pressure plasma film deposition by so-called dielectric barrier discharge can be used. As an example of the cylindrical electrode 12, an electrode is provided in which the surface of a cylinder made of a conductive material such as metal is covered with a dielectric material such as quartz glass.

[0021] The film deposition unit 14 is a metal block-shaped component. The film deposition unit 14 has a channel forming section 20 at its lower central end in the lateral direction. The channel forming section 20 is a cylindrical space with an inner diameter larger than the outer diameter of the cylindrical electrode 12, and the height direction is perpendicular to the plane of the paper. The lower end of the channel forming section 20 opens from the lower end of the film deposition unit 14. That is, the film deposition unit 14 has a slit-shaped outlet 20a at its lower central end in the lateral direction, with its longitudinal direction perpendicular to the plane of the paper. Furthermore, a plasma generation gas supply passage 24 is provided, extending from the upper end of the flow path forming section 20 to the upper surface of the film deposition unit 14. A plasma generation gas supply source, not shown in the figures, is connected to the plasma generation gas supply passage 24.

[0022] In the film deposition apparatus 10, the space between the cylindrical electrode 12 and the film deposition unit 14 serves as an internal flow path for introducing the plasma generation gas. In other words, the space between the cylindrical electrode 12 and the inner wall surface of the flow path forming section 20 serves as an internal flow path. Therefore, the plasma generation gas is generated by dielectric barrier discharge as it passes through the internal flow path between the cylindrical electrode 12 and the film deposition unit 14 from the plasma generation gas supply path 24, and is introduced between the electrode pair and the substrate from the outlet 20a on the lower surface of the film deposition unit 14. In other words, the outlet 20a is the outlet for the gas from the internal flow path.

[0023] The film deposition unit 14 is provided with a first raw material gas supply passage 26 and a second raw material gas supply passage 28 so as to sandwich the flow path forming section 20 in the lateral direction. Both the first raw material gas supply passage 26 and the second raw material gas supply passage 28 are cylindrical spaces with a height direction perpendicular to the plane of the paper. Both the first raw material gas supply channel 26 and the second raw material gas supply channel 28 are connected to raw material gas supply sources, which are not shown in the diagram.

[0024] The film deposition unit 14 is further provided with a first outer channel 30 and a second outer channel 32. The first outer channel 30 is connected from the first raw material gas supply channel 26 to the outlet 30a on the lower surface of the film deposition unit 14. The outlet 30a is located to the left of the outlet 20a of the inner channel. The outlet 30a is a slit-shaped opening with its longitudinal direction perpendicular to the plane of the paper. The second outer channel 32 is connected from the second raw material gas supply channel 28 to the outlet 32a on the lower surface of the film deposition unit 14. The outlet 32a is located to the right of the outlet 20a of the inner channel. The outlet 32a is a slit-shaped opening with its longitudinal direction perpendicular to the plane of the paper. The lengths of the outlet 20a of the inner channel described above, as well as the slits of the outlet 30a of the first outer channel 30 and the outlet 32a of the second outer channel 32, can all be set appropriately according to the length of the substrate Z in the direction perpendicular to the plane of the paper on which the film deposition is to be carried out.

[0025] In this invention, the designations "first" and "second" attached to each component, as well as "first" and "second" in the first and second gas flow rates described later, are merely for convenience to distinguish them and have no technical significance. Therefore, the terms "first" and "second" are unrelated to their respective positional relationships, functions, gas flow rates, or upstream / downstream gas flow.

[0026] In atmospheric pressure plasma deposition, the electrode pair and the substrate are typically moved relative to each other while the film is deposited on the substrate Z. In atmospheric pressure plasma deposition, the substrate Z is often transported to move the electrode pair and the substrate relative to each other. In atmospheric pressure plasma deposition using remote diffusion mixing, the outer channel (outlet) for introducing the source gas is usually positioned so as to sandwich the inner channel (outlet) in the direction of substrate transport. Therefore, in the film deposition apparatus 10, in a preferred embodiment, the outlet 30a of the first outer channel 30 and the outlet 32a of the second outer channel 32 are provided so as to sandwich the outlet 20a of the inner channel in the transport direction of the substrate Z. Furthermore, in a preferred embodiment, the outlet 20a of the inner channel, the outlet 30a of the first outer channel 30, and the outlet 32a of the second outer channel 32 are slit-shaped with a longitudinal direction perpendicular to the transport direction of the substrate Z.

[0027] In the present invention, the relative movement between the electrode pair and the substrate Z may be performed by fixing the electrode pair and transporting the substrate Z as described above, or by fixing the substrate Z and transporting the electrode pair, or by moving both the electrode pair and the substrate Z. Although not shown in the illustration, the film deposition apparatus 10 in the illustrated example has a substrate Z transport means. The substrate Z transport means is a substrate holding means in the film deposition apparatus of the present invention. The substrate Z transport means is a known substrate transport means used in atmospheric pressure plasma film deposition using a remote diffusion mixing method. In addition, in this invention, the electrode pair and the substrate Z may be stationary, without moving them relative to each other, while the film is being deposited on the substrate Z.

[0028] Furthermore, the film deposition method and film deposition apparatus of the present invention are not limited to a configuration using cylindrical electrodes, as shown in the film deposition apparatus 10 in Figure 1. In other words, as described later, the present invention allows the use of various known remote diffusion mixing atmospheric pressure plasma deposition methods by making the first gas flow rate and the second gas flow rate uneven. Examples include atmospheric pressure plasma deposition using a configuration such as the one shown in Patent Document 1 above, in which the space between two parallel-arranged flat plate electrodes serves as the inner flow path, and the first and second outer flow paths located below the flat plate electrodes, and atmospheric pressure plasma deposition using a configuration such as the one shown in Figure 8. In this case, the flat electrode has corners. Therefore, if the electrode and the substrate are brought close together, there is a possibility of abnormal discharge occurring. In contrast, the cylindrical electrode does not have corners, so even if the electrode and the substrate are brought close together, the possibility of abnormal discharge occurring is extremely low. Considering this point, in the present invention, it is preferable to use a cylindrical electrode 12, such as the film deposition apparatus 10 in the illustrated example, rather than a flat electrode.

[0029] In the film deposition apparatus 10, an AC power supply 16 is connected to the cylindrical electrode 12. Furthermore, the cylindrical electrode 12 and the film deposition unit 14 that constitute the electrode pair are grounded. Therefore, by applying an AC voltage to the cylindrical electrode 12, a dielectric barrier discharge occurs between the cylindrical electrode 12 and the film deposition unit 14 (the inner wall surface of the channel forming section 20). This excites the plasma generation gas flowing between the cylindrical electrode 12 and the film deposition unit 14, which are internal channels, and generates plasma.

[0030] The AC power supply 16 is a known high-frequency AC power supply used in atmospheric pressure plasma film deposition using a remote diffusion mixing method. In the present invention, there are no restrictions on the frequency (frequency of the plasma excitation voltage) and output (plasma excitation power) of the AC power supply 16. These can be set appropriately according to the film to be deposited, the source gas and plasma generation gas, and the desired film deposition rate. In addition, in this invention, a pulse power supply may be used instead of an AC power supply.

[0031] In the film deposition apparatus 10 shown in Figure 1, when depositing a film on the substrate Z, an AC voltage is applied to the cylindrical electrode 12, similar to known remote diffusion mixing atmospheric pressure plasma deposition methods, while a plasma generation gas is supplied between the cylindrical electrode 12, which is an internal channel, and the deposition unit 14 (inner wall surface of the channel forming section 20). This excites the plasma generation gas passing through the internal channel, generating plasma, and the plasma generation gas containing the plasma is introduced from the outlet 20a between the electrode pair and the substrate Z. As described above, in the film deposition apparatus 10, the electrode pair is formed between the cylindrical electrode 12 and the deposition unit 14. In parallel, raw material gas is supplied to the first outer channel 30 and the second outer channel 32, and the raw material gas is introduced between the electrode and the substrate Z from the outlets 30a and 32a. This process diffuses and mixes the plasma and source gas between the electrode pair and the substrate Z, activating the source gas and depositing a film on the substrate Z using the active species of the generated source gas. In the following explanation, the region between the electrode pair and the substrate Z where the plasma and source gas diffuse and mix will also be simply referred to as the "mixing region."

[0032] In the film deposition apparatus 10 (film deposition method) of the present invention, when the gas flow rate between the outlet 30a of the first outer channel 30 and the substrate Z is defined as the first gas flow rate, and the gas flow rate between the outlet 32a of the second outer channel 32 and the substrate Z is defined as the second gas flow rate, the first gas flow rate and the second gas flow rate are made unequal in order to deposit a film on the substrate Z. The gas flow rate referred to here is the gas flow rate between the electrode pair and the substrate Z, flowing in the plane direction of the substrate Z, either from the first outer channel 30 to the second outer channel 32, or from the second outer channel 32 to the first outer channel 30, through an arbitrary cross-section. As an example of an arbitrary cross-section, the channel cross-section below the exhaust port 32a, which is perpendicular to the substrate Z and the plane of the paper, is exemplified. In the illustrated example, as an example, the amount of gas introduced (flow rate) from the first outer channel 30 to the mixing section and the amount of gas introduced from the second outer channel 32 to the mixing section are made different, thereby creating an uneven flow rate between the first and second gas flows, and a film is formed on the substrate Z. In this invention, having such a configuration suppresses the aggregation of active species in the raw material gas and the generation of fine particles, making it possible to deposit a highly flat film at a high deposition rate.

[0033] As described above, in atmospheric pressure plasma film deposition using a remote diffusion mixing method, in order to improve the decomposition ability of the source gas and increase the film deposition rate, it is preferable to increase the residence time of the source gas in the mixing section between the electrode pair and the substrate, thereby increasing the mixing reaction time between the plasma and the source gas. For example, the amount of gas introduced into the first outer channel 30 and the amount of gas introduced into the second outer channel 32 are made equal. This suppresses the gas flow in the mixing section between the electrode pair and the substrate Z, as conceptually shown in Figure 3. As a result, the residence time of the raw material gas in the mixing section is increased, and the mixing reaction time between the plasma and the raw material gas is extended. On the other hand, in film deposition using atmospheric pressure plasma, if the decomposed raw material gas (active species) remains in the gas phase mixing area for a long time, the active species of the raw material gas will condense and form fine particles. When such fine particles adhere to the substrate, the flatness of the deposited film is impaired, and the quality deteriorates.

[0034] Figure 4 conceptually illustrates the relationship between the reaction progress in the mixing section of an atmospheric pressure plasma film deposition system using remote diffusion mixing, the concentration of the decomposed source gas, i.e., the active species (solid line), and the aggregated particle size of the particles formed from aggregated active species (dashed line). According to the inventors' studies, as shown in Figure 4, as the reaction in the mixing section progresses, the concentration of the decomposed raw material gas, i.e., the active species, increases. Also, as shown in Figure 4, when the active species reach a certain concentration, aggregation of the active species begins, and the aggregated particle size increases as the reaction progresses. As a result, once the reaction progresses beyond a certain point, the aggregated particle size due to the aggregation of active species exceeds the allowable particle size. The reaction progress is a variable that conceptually represents the degree to which the reaction between the raw material gas and the plasma progresses, influenced by the residence time, temperature, activation energy, and diffusion coefficient of the raw material gas in the mixing section.

[0035] The film deposition rate is affected by the concentration of active species. Therefore, by increasing the reaction rate to a certain extent, the concentration of active species can be ensured, and the film deposition rate can be increased. On the other hand, as shown in Figure 4, by limiting the reaction rate to a certain level or lower, the aggregated particle size can be suppressed to below the acceptable particle size.

[0036] Here, the rate of reaction progress is influenced by the residence time, temperature, activation energy, and diffusion coefficient of the raw material gas in the mixing section. Therefore, the rate of reaction can be controlled by controlling the residence time of the raw material gas in the mixing section. Furthermore, by controlling the rate of reaction, the concentration of active species in the mixing section can be maintained near its maximum value to ensure a sufficient film formation rate, and the aggregated particle size can be suppressed to below the allowable particle size. This invention was made possible by obtaining such knowledge, by making the first gas flow rate, which is the gas flow rate between the outlet 30a of the first outer channel 30 and the substrate Z, and the second gas flow rate, which is the gas flow rate between the outlet 32a of the second outer channel 32 and the substrate Z, uneven. By doing so, this invention controls the residence time of the raw material gas in the mixing section, i.e., the rate of reaction progress, and as shown in the compatible region in Figure 4, it is possible to achieve both securing the reaction rate and suppressing the aggregation of active species, thereby enabling the deposition of a high-quality film with high flatness at a high deposition rate. In other words, the present invention controls the flow of the raw material gas in the mixing section in the low-speed range by making the first gas flow rate and the second gas flow rate uneven. That is, the present invention makes the flow velocity of the raw material gas in the mixing section close to zero by making the first gas flow rate and the second gas flow rate uneven, and then allows a small amount of raw material gas to flow. This invention improves the film deposition rate by ensuring sufficient residence time for the raw material gas in the mixing section, i.e., the mixing time between the raw material gas and the plasma, while also preventing the residence time of the raw material gas in the mixing section from becoming unnecessarily long, thereby suppressing the aggregation of active species and enabling the deposition of a flat film.

[0037] In the illustrated example, as an example, the amount of gas introduced into the mixing section from the second outer channel 32 is made greater than the amount of gas introduced into the mixing section from the first outer channel 30. This creates a low-speed gas flow in the plane direction of the substrate Z, from the outlet 32a of the second outer channel 32 to the outlet 30a of the first outer channel 30, as conceptually shown in Figure 2, thereby making the first gas flow rate greater than the second gas flow rate. In the illustrated example of the film deposition apparatus 10, this controls the residence time of the raw material gas in the mixing section, thereby achieving both an improved film deposition rate and suppression of aggregation of active species.

[0038] As described above, in atmospheric pressure plasma deposition using the remote diffusion mixing method, the electrode pair and the substrate Z are usually moved relative to each other to perform the deposition. However, in the present invention, even when film deposition is performed by relatively moving the electrode pair and the substrate Z, it is sufficient that the first gas flow rate and the second gas flow rate are unequal when the relative movement between the electrode pair and the substrate Z is stopped. That is, in the present invention, the first gas flow rate and the second gas flow rate are measured when the relative movement between the electrode pair and the substrate Z is stopped, and it is determined whether the first gas flow rate and the second gas flow rate are equal or unequal.

[0039] Furthermore, the present invention is particularly suitable for cases where the relative movement speed between the electrode pair and the substrate Z is low. Specifically, in the present invention, the relative movement speed between the electrode pair and the substrate Z is preferably 1.0 m / min or less, and more preferably 0.2 m / min or less. As described above, the present invention includes forming a film without relatively moving the electrode pair and the substrate Z. Therefore, there is no lower limit to the relative movement speed between the electrode pair and the substrate Z.

[0040] In this invention, there is no limit to the difference between the first gas flow rate and the second gas flow rate, as long as they are unequal. In other words, when the higher flow rate of the first gas flow rate and the lower flow rate of the second gas flow rate are designated as flow rate A and flow rate B respectively, there is no limit to the flow rate ratio A / B between flow rate A and flow rate B; it just needs to be greater than 1. In other words, in the present invention, the optimal flow rate ratio A / B varies depending on the type of process gas and raw material gas, the concentration of each gas supplied to each flow path, the target film deposition rate, the shape and configuration of the electrodes, and the power and frequency of the AC voltage applied to the cylindrical electrode 12. Therefore, the flow rate ratio A / B between the first gas flow rate and the second gas flow rate should be set appropriately according to these factors.

[0041] The flow rate ratio A / B is preferably 1.0001 to 10000, and more preferably 1.01 to 10. By setting the flow rate ratio A / B within this range, the residence time of the raw material gas in the mixing section can be suitably controlled, enabling the formation of a film with higher flatness at a higher deposition rate.

[0042] In this invention, depending on the configuration and size of the film deposition apparatus, the shape of the electrodes, and the gap between the electrodes and the substrate Z, it may not be possible to measure the first gas flow rate and the second gas flow rate between the outlet 30a of the first outer channel 30 and the substrate Z, and between the outlet 32a of the second outer channel 32 and the substrate Z. In such cases, the first gas flow rate and the second gas flow rate should be measured at a position where the gas flow rate can be measured, on the extension of the line in the direction in which the outlet 30a of the first outer flow path 30 and the outlet 32a of the second outer flow path 32 are separated. For example, when film deposition is performed while transporting the substrate Z as described above, the first outer channel 30 (discharge port 30a) and the second outer channel 32 (discharge port 32a) are provided on either side of the inner channel (discharge port 20a) in the transport direction. Therefore, when transporting the substrate Z from the first outer channel 30 toward the second outer channel 32, the first gas flow rate and the second gas flow rate should be measured at positions where the gas flow rate can be measured, upstream of the discharge port 30a and downstream of the discharge port 32a in the transport direction of the substrate Z.

[0043] As described above, the present invention makes the gas flow rate between the outlet 30a of the first outer flow path 30 and the substrate Z the first gas flow rate, and the gas flow rate between the outlet 32a of the second outer flow path 32 and the substrate Z the second gas flow rate, thereby making the first gas flow rate and the second gas flow rate unequal. Therefore, the direction of gas flow between the substrate Z and the electrode is approximately from outlet 30a to outlet 32a, or vice versa. Therefore, by measuring the gas flow rate along the extension of the line in the direction in which outlets 30a and 32a are separated, it is possible to determine whether the first gas flow rate and the second gas flow rate are equal or unequal. Furthermore, the flow rate ratio of the gas flow rates measured along the extension of the line in the direction in which outlets 30a and 32a are separated will be approximately equivalent to the flow rate ratio A / B of the first gas flow rate and the second gas flow rate. For example, in the case of the film deposition apparatus 10 shown in the illustration, the gas flow rate can be measured at the lateral end of the film deposition unit 14, which is on the extension of the line in the direction in which the outlets 30a and 32a are separated.

[0044] In the present invention, it is not necessarily limited to introducing the raw material gas from both the first outer flow path 30 and the second outer flow path 32. In other words, the raw material gas may be introduced only through one of the first outer channel 30 and the second outer channel 32, while the other channel may be used to introduce only an inert gas, such as the plasma generation gas. In this case, it is preferable to introduce the raw material gas through the outer channel with the larger gas introduction rate, in terms of controllability of the gas flow. However, it is preferable to introduce the raw material gas from both the first outer channel 30 and the second outer channel 32, as this allows for a higher film deposition rate.

[0045] As described above, in the illustrated example of the film deposition apparatus 10, the flow rate control means in the film deposition apparatus of the present invention is to make the first gas flow rate and the second gas flow rate uneven by making the amount of gas introduced from the first outer channel 30 to the mixing section and the amount of gas introduced from the second outer channel 32 to the mixing section different. However, in the present invention, the method for making the first gas flow rate and the second gas flow rate uneven, that is, the flow rate control means in the film deposition apparatus of the present invention, is not limited to this, and various methods can be used.

[0046] As an example, one method is to make the first and second gas flow rates unequal by setting the gas introduction amounts from the first outer flow path 30 and the second outer flow path 32 to be equal, and making the outlet 30a of the first outer flow path 30 and the outlet 32a of the second outer flow path 32 to be of different areas. In the illustrated example, one method is to make the first and second gas flow rates unequal by making the widths of the slits to be of different widths. For example, assuming a uniform gas introduction rate, the width of the slit at outlet 32a is made smaller than that of outlet 30a. As a result, the gas flow velocity introduced from outlet 32a becomes faster than that introduced from outlet 30a. Consequently, similar to Figure 2, a gas flow is formed in the planar direction of the substrate Z, from outlet 32a of the second outer flow path 32 towards outlet 30a of the first outer flow path 30, making the first gas flow rate greater than the second gas flow rate.

[0047] As an alternative method, an example is provided in which a gas supply means is provided on the side of the first outer flow path 30 (discharge port 30a) or the second outer flow path 32 (discharge port 32a) opposite to the inner flow path (discharge port 20a), and a membrane-like gas (curtain gas) is supplied from this gas supply means to make the first gas flow rate and the second gas flow rate uneven. For example, in the film deposition unit 14, a gas film forming means is provided on the side of the second outer channel 32 opposite to the inner channel, and a curtain gas is supplied toward the substrate Z. This curtain gas blocks the gas flow from the second outer channel 32 toward the right. As a result, similar to Figure 2, a gas flow is formed in the plane direction of the substrate Z, from the outlet 32a of the second outer channel 32 toward the outlet 30a of the first outer channel 30, and the first gas flow rate can be made larger than the second gas flow rate.

[0048] Another method involves providing an exhaust means on the side of the first outer flow path 30 (discharge port 30a) or the second outer flow path 32 (discharge port 32a) opposite to the inner flow path (discharge port 20a), and exhausting gas from this exhaust means to make the first gas flow rate and the second gas flow rate uneven. For example, in the film deposition unit 14, an exhaust means is provided on the side of the first outer channel 30 opposite to the inner channel, and gas is exhausted from there. As a result, similar to Figure 2, a gas flow is formed in the plane direction of the substrate Z from the outlet 32a of the second outer channel 32 toward the outlet 30a of the first outer channel 30, and the first gas flow rate can be made larger than the second gas flow rate.

[0049] Another method involves creating a pressure distribution between the substrate Z and the electrode by making the shape of the region of the electrode facing the substrate Z different on the first outer channel 30 side and the second outer channel 32 side, thereby making the first gas flow rate and the second gas flow rate uneven. For example, in the film deposition unit 14, the distance between the film deposition unit 14 and the substrate Z on the second outer channel 32 side is made smaller than the distance between the film deposition unit 14 and the substrate Z on the first outer channel 30 side. As a result, the pressure between the substrate Z and the substrate Z becomes higher on the second outer channel 32 side than on the first outer channel 30 side, and, as in Figure 2, a gas flow is formed in the plane direction of the substrate Z from the outlet 32a of the second outer channel 32 toward the outlet 30a of the first outer channel 30, making the first gas flow rate greater than the second gas flow rate.

[0050] In addition, in the present invention, two or more of these methods may be used in combination to make the first gas flow rate and the second gas flow rate uneven. Furthermore, these methods can also be used with the configuration shown in Patent Document 1 and Figure 8.

[0051] Although the film deposition method and atmospheric pressure plasma film deposition apparatus of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various improvements and modifications may be made without departing from the spirit of the present invention. [Examples]

[0052] The present invention will be described in more detail below with reference to specific embodiments. However, the present invention is not limited to the following embodiments.

[0053] [Examples] A DLC film was deposited on the substrate Z using the film deposition apparatus 10 shown in Figure 1. Substrate Z used a silicon substrate with a thickness of 0.8 mm.

[0054] The distance between the bottom of the cylindrical electrode 12 and the bottom surface of the film deposition unit 14 and the substrate Z was set to 2 mm. The cylindrical electrode 12 was made by covering the surface of a stainless steel cylinder with a diameter of 17 mm and a height of 60 mm with quartz glass that was 1.5 mm thick. The film deposition unit 14 was made of stainless steel. A cylindrical channel forming section 20 was provided in the lateral center of the film deposition unit 14, with its bottom opening. Furthermore, a plasma generation gas supply passage 24 was formed so as to communicate with the channel forming section 20. A cylindrical electrode 12 was inserted into the channel forming section 20, with its center aligned with the cylinder. The distance between the cylindrical electrode 12 and the film deposition unit 14 (inner wall surface of the channel forming section 20) was set to 1.5 mm. As described above, the space between the cylindrical electrode 12 and the film deposition unit 14 forms the inner channel. Furthermore, the film deposition unit 14 was formed with a first raw material gas supply passage 26 and a first outer channel 30, and a second raw material gas supply passage 28 and a second outer channel 32. The slit width of the outlet 30a of the first outer channel 30 and the outlet 32a of the second outer channel 32 was set to 0.5 mm. In addition, in both outer channels, the region facing the outlet was set at an angle of 18° (162°) with respect to the horizontal direction.

[0055] An AC power supply 16 with a frequency of 27.12 MHz was connected to the cylindrical electrode 12. Furthermore, the film deposition unit 14 was grounded.

[0056] A film was deposited on the substrate Z using this film deposition apparatus 10. A mixed gas consisting of 99.1 vol% argon, 0.7 vol% nitrogen, and 0.2 vol% oxygen was supplied to the inner flow path. The rate of introduction of the mixed gas into the mixing section was 2.3 L / min. Meanwhile, a mixed gas of 99 vol% argon gas and 1 vol% propane gas was supplied to the first outer channel 30 and the second outer channel 32. The output of AC power supply 16 was set to 600W. The deposition atmosphere was set to room temperature and atmospheric pressure. The film deposition was performed with the substrate Z stationary (substrate transport speed 0 mm / sec).

[0057] Under the above conditions, the gas introduction rate from the first outer channel 30 to the mixing section was kept constant at 6.7 L / min, and the gas introduction rate from the second outer channel 32 to the mixing section was changed to 6.7 L / min, 6.8 L / min, 7.3 L / min, 8.0 L / min, 8.8 L / min, and 16.8 L / min, and film deposition was performed. As another example, the gas introduction rate from the second outer channel 32 to the mixing section was kept constant at 6.7 L / min, and the gas introduction rate from the first outer channel 30 to the mixing section was changed to 0.67 L / min and 0.067 L / min, and film deposition was performed. Therefore, the ratio of the gas introduced from the first outer channel 30 to the gas introduced from the second outer channel 32 (the ratio of the gas introduced from the second outer channel to the gas introduced from the first outer channel) is 1, 1.01, 1.1, 1.2, 1.3, 2.5, 10, and 100.

[0058] Furthermore, during film formation, the gas flow velocity [m / sec] was measured outside the first outer channel 30 side and outside the second outer channel 32 side of the film formation unit 14 in the lateral direction, i.e., in the direction in which the first outer channel 30 and the second outer channel 32 are separated. The results are shown in Figure 5. In Figure 5, the flow velocity is shown specifically for representative data, specifically for introduction volume ratios of 1, 1.1, 1.2, and 1.3. As shown in Figure 5, in cases where the introduction rate ratio is other than 1, there is a large difference in flow velocity between the outside of the first outer channel 30 and the outside of the second outer channel 32. Therefore, in cases where the introduction rate ratio is other than 1, the first gas flow rate between the outlet 30a of the first outer channel 30 and the substrate Z and the second gas flow rate between the outlet 32a of the second outer channel 32 and the substrate Z are unequal. Specifically, as described above, in this example, the distance between the film deposition unit 14 and the substrate Z is 2 mm. Also, the length of the film deposition unit 14 in the direction perpendicular to the plane of the paper is 60 mm. Therefore, at an introduction ratio of 1.0, the gas flow rates on the first outer channel 30 and the second outer channel 32 are 5.6 L / min. At an introduction ratio of 1.01, the gas flow rate on the first outer channel 30 side is 5.6 L / min, and the gas flow rate on the second outer channel 32 side is 5.5 L / min. At an introduction ratio of 1.1, the gas flow rate on the first outer channel 30 side is 5.8 L / min, and the gas flow rate on the second outer channel 32 side is 3.7 L / min. At an introduction ratio of 1.2, the gas flow rate on the first outer channel 30 side is 6.8 L / min, and the gas flow rate on the second outer channel 32 side is 4.7 L / min. At an introduction ratio of 1.3, the gas flow rate on the first outer channel 30 side is 8.3 L / min, and the gas flow rate on the second outer channel 32 side is 4.7 L / min. At an introduction ratio of 2.5, the gas flow rate on the first outer channel 30 side is 16.2 L / min, and the gas flow rate on the second outer channel 32 side is 4.2 L / min. At an introduction rate ratio of 10, the gas flow rate on the first outer channel 30 side is 4.8 L / min, and the gas flow rate on the second outer channel 32 side is 1.5 L / min. Furthermore, At an introduction rate ratio of 100, the gas flow rate on the first outer channel 30 side is 4.0 L / min, and the gas flow rate on the second outer channel 32 side is 1.8 L / min.

[0059] For films deposited at each gas introduction ratio, the deposition rate and surface roughness Ra (arithmetic mean roughness Ra) were measured. The results are shown in Figure 6. Figure 7 shows the results for the range of gas introduction ratios from 1 to 1.3, magnified. The film deposition rate was normalized based on an example with a flow rate ratio of 1. Furthermore, the surface roughness Ra was measured using an atomic force microscope in accordance with JIS B 0601 2001. In Figures 6 and 7, the dashed line represents the deposition rate, and the dotted line represents the surface roughness Ra.

[0060] As shown in Figures 6 and 7, by making the amount of gas introduced into the mixing section uneven in the first outer channel 30 and the second outer channel 32, that is, by making the first gas flow rate between the outlet 30a of the first outer channel 30 and the substrate Z and the second gas flow rate between the outlet 32a of the second outer channel 32 and the substrate Z uneven, the film deposition rate and surface roughness Ra of the film being deposited will fluctuate. In this example, by setting the introduction ratio of the second outer channel to the first outer channel to 1.1, it is possible to maintain a film deposition rate equivalent to that of an introduction ratio of 1, which is considered to have the longest residence time of the raw material gas in the mixing section and the highest film deposition rate, while achieving a surface roughness Ra of approximately 1.5 nm. Based on the above results, the effects of the present invention are clear. [Industrial applicability]

[0061] It can be suitably used for film formation in the manufacturing of various products. [Explanation of Symbols]

[0062] 10 (Atmospheric pressure plasma) film deposition apparatus 12 Cylindrical electrodes 14. Film deposition unit 16 AC power supply 20 Flow channel forming section 20a,30a,32a outlet 24. Gas supply channel for plasma generation 26. First raw material gas supply route 28. Second raw material gas supply route 30 First outer channel 32 Second outer channel 100 electrode pairs 102 External electrode PG (Power Generation Gas) for Plasma Generation MG raw material gas

Claims

1. When forming a film on a substrate with a flat surface to be processed by atmospheric pressure plasma, a plasma generating gas is introduced from an inner channel passing between the electrode pair, and a raw material gas is introduced from at least one of a first outer channel and a second outer channel located outside the electrode pair, between the electrode pair and the electrode pair, one of which is a cylindrical electrode and the height direction of the cylindrical electrode is arranged parallel to the surface to be processed on the substrate, When the gas flow rate between the outlet of the first outer channel and the substrate is defined as the first gas flow rate, and the gas flow rate between the outlet of the second outer channel and the substrate is defined as the second gas flow rate, the first gas flow rate and the second gas flow rate are made uneven, and a film is formed on the substrate. A film formation method characterized in that the flow rate ratio of the first gas flow rate to the second gas flow rate is 1.01 to 10.

2. The film formation method according to claim 1, wherein the raw material gas is introduced from an outer channel corresponding to at least the side with the higher flow rate of the first gas flow rate and the second gas flow rate.

3. The method for forming a film according to claim 1 or 2, wherein the raw material gas is introduced from both the first outer channel and the second outer channel.

4. The film formation method according to any one of claims 1 to 3, wherein the amount of gas introduced from the first outer channel and the amount of gas introduced from the second outer channel are different, thereby making the first gas flow rate and the second gas flow rate unequal.

5. The film formation method according to any one of claims 1 to 4, wherein the outlet of the first outer channel and the outlet of the second outer channel are made to have different areas, thereby making the first gas flow rate and the second gas flow rate unequal.

6. A film formation method according to any one of claims 1 to 5, wherein an air supply means is provided on the side of one of the first outer flow path and the second outer flow path opposite to the inner flow path, and the first gas flow rate and the second gas flow rate are made uneven by supplying air from the air supply means.

7. A film formation method according to any one of claims 1 to 6, wherein an exhaust means is provided on the side of one of the first outer flow path and the second outer flow path opposite to the inner flow path, and the first gas flow rate and the second gas flow rate are made uneven by exhausting gas from this exhaust means.

8. Electrode pair and, A substrate holding means for holding a substrate with a flat surface to be processed, An inner channel for introducing gas between the electrode pair and the substrate holding means, passing between the electrode pair and the substrate holding means, A first outer channel and a second outer channel introduce gas between the electrode pair and the substrate holding means, passing outside the space between the electrode pair and the substrate holding means. The system includes a flow rate control means that makes the gas flow rate between the outlet of the first outer channel and the substrate holding means an uneven first gas flow rate, and the gas flow rate between the outlet of the second outer channel and the substrate holding means an uneven second gas flow rate. One of the electrode pair is a cylindrical electrode, and the height direction of the cylindrical electrode is arranged parallel to the surface of the substrate to be processed. An atmospheric pressure plasma film deposition apparatus characterized in that the flow rate ratio of the first gas flow rate to the second gas flow rate is 1.01 to 10.

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