Processing method, processing device and processing system

Abstract

To provide a processing method with improved processing efficiency. [Solution] The treatment method involves irradiating a treatment gas containing carbon dioxide, having an oxygen concentration of 1000 ppm or less, and a water vapor concentration of 5 ppm to 30000 ppm with ultraviolet light having an emission wavelength of 227 nm or less, and treating the object by bringing the treatment gas irradiated with the ultraviolet light into contact with the object.

Description

[Technical Field]

[0001] The present invention relates to a processing method, a processing apparatus, and a processing system for processing an object to be processed using activated species of a raw material gas containing carbon dioxide. [Background technology]

[0002] In an atmosphere containing oxygen gas, vacuum ultraviolet light with a wavelength of 172 nm is irradiated onto the workpiece to generate ozone, which is then converted into excited atomic oxygen O( 1 D) to modify or clean the surface of a workpiece (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-152842 Summary of the Invention [Problem to be solved by the invention]

[0004] Ground state atomic oxygen O( 3 P) and excited atomic oxygen O( 1 D) (hereinafter, these may be collectively referred to as "atomic oxygen") is an effective raw material for surface modification and cleaning of the workpiece. In order to improve the processing efficiency, the first thing that comes to mind is to increase the oxygen gas concentration in the atmosphere to increase the amount of atomic oxygen. However, when the oxygen gas concentration in the atmosphere is increased, the vacuum ultraviolet light is absorbed by the oxygen gas in the atmosphere, and the amount of vacuum ultraviolet light that reaches the surface of the workpiece (i.e., the illuminance on the surface of the workpiece) decreases.

[0005] If the problem were limited to reduced illuminance, it would be possible to reduce the amount of vacuum ultraviolet light absorbed by oxygen gas by bringing the vacuum ultraviolet light source closer to the object to be treated. However, there was also the problem that atomic oxygen obtained from oxygen gas tends to return to ozone upon collision with surrounding oxygen molecules, leaving room for improvement in terms of treatment efficiency.

[0006] An object of the present invention is to provide a processing method, processing device, and processing system with improved processing efficiency. [Means for solving the problem]

[0007] The treatment method of the present invention includes irradiating a treatment gas containing carbon dioxide, having an oxygen concentration of 1000 ppm or less, and having a water vapor concentration of 5 ppm or more and 30000 ppm or less, with ultraviolet light having an emission wavelength of 227 nm or less; The processing gas irradiated with the ultraviolet light is brought into contact with the object to be processed, thereby processing the object.

[0008] The reason for conceiving the above-mentioned processing method is explained below. First, the inventor conceived of obtaining atomic oxygen from carbon dioxide gas. That is, carbon dioxide gas is used as the processing gas. The processing gas contains carbon dioxide and contains almost no oxygen gas, which easily returns to ozone upon collision with surrounding oxygen molecules. The concentration of oxygen gas in the processing gas is set to 1000 ppm or less. The processing gas is irradiated with ultraviolet light having an emission wavelength of 227 nm or less, and the processing gas irradiated with the ultraviolet light is brought into contact with the processing object to process the processing object.

[0009] As will be explained in more detail later, when carbon dioxide is irradiated with ultraviolet light with an emission wavelength of 227 nm or less, atomic oxygen O( 1 D) or atomic oxygen O( 3 As mentioned above, atomic oxygen can be obtained from oxygen gas by irradiating it with ultraviolet light. However, in an atmosphere containing a large amount of oxygen gas, O( 3P) combines with oxygen molecules in the atmosphere and is converted into ozone. On the other hand, since oxygen gas is barely present in the source gas, at 1000 ppm or less, a large amount of atomic oxygen O( 3 P) can be maintained. A large amount of atomic oxygen O( 3 P) can be used to modify and clean the surface of the object to be treated. This is the greatest advantage of using a raw material gas that contains carbon dioxide and has an oxygen gas concentration of 1000 ppm or less.

[0010] When carbon dioxide is used as a raw material gas, irradiating the raw material gas with ultraviolet light generates atomic oxygen and carbon monoxide at the same time. Because carbon monoxide is harmful to living organisms, it is desirable to discharge gas with a reduced carbon monoxide concentration from the treatment device. Therefore, after extensive research, the inventors came up with the idea of ​​using a treatment gas containing water vapor. A treatment gas containing carbon dioxide and water vapor is irradiated with ultraviolet light. When the water vapor is irradiated with ultraviolet light, OH radicals are generated. The OH radicals convert carbon monoxide to carbon dioxide. Furthermore, the OH radicals promote the treatment of the object to be treated. In other words, using a gas containing water vapor as a treatment gas not only contributes to a hygienic environment, but also to improved treatment efficiency.

[0011] To generate OH radicals that convert carbon monoxide to carbon dioxide, the water vapor concentration in the process gas should be at least 5 ppm. If the water vapor concentration in the process gas is too high, the process gas will condense, forming droplets inside the process chamber, or the water vapor will absorb more ultraviolet light than necessary, attenuating the intensity of the ultraviolet light. Therefore, the water vapor concentration in the process gas should be 30,000 ppm or less.

[0012] In this specification, when ultraviolet light is specified by its emission wavelength, it does not matter whether the ultraviolet light has intensity at wavelengths other than the specified wavelength range. For example, "ultraviolet light having an emission wavelength of 227 nm or less" means that all ultraviolet light that shows intensity in the wavelength range of 227 nm or less falls under "ultraviolet light having an emission wavelength of 227 nm or less," regardless of whether the ultraviolet light has intensity in the wavelength range above 227 nm in its emission spectrum. Note that the specification also uses the expression "light having a main emission wavelength of 227 nm or less," and the meaning of this expression will be described later.

[0013] In the treatment method, the concentration of carbon dioxide contained in the treatment gas may be 5 vol% or more. When the concentration of carbon dioxide is 5 vol% or more, the O( 3 P), the production efficiency is increased. In this specification, "raw material gas" refers to a gas containing carbon dioxide. In this specification, "processing gas" refers to a gas containing water vapor in addition to carbon dioxide. The "raw material gas" or "processing gas" may contain an inert gas such as nitrogen gas. The inert gas contained in the "raw material gas" or "processing gas" may reduce the concentration of carbon dioxide in the "raw material gas" or "processing gas."

[0014] The processing gas may be generated by adding water vapor to a raw material gas containing carbon dioxide and having an oxygen concentration of 1000 ppm or less.

[0015] The water vapor concentration in the processing gas may be 50 ppm or more. This allows sufficient OH radicals to be generated to convert carbon monoxide to carbon dioxide. The water vapor concentration may be further increased, for example, to more than 100 ppm. This allows more OH radicals to be generated, and the carbon monoxide concentration to be kept lower.

[0016] The process gas may be brought into contact with the object to be processed inside a process chamber isolated from the atmosphere.

[0017] The ultraviolet light may be irradiated onto the processing gas present in the atmosphere in which the object to be processed is located. Such a processing method can be realized, for example, by using processing apparatuses shown in the first to fifth embodiments (FIGS. 1, 2, 6, 9, 10, 11A, and 11B) described below.

[0018] The processing gas irradiated with the ultraviolet light may be sprayed onto the object to be processed. Such a processing method can be realized by using a spray-type processing apparatus shown in the sixth to eighth embodiments (FIGS. 12, 13, and 14) described later. When the processing gas irradiated with ultraviolet light is sprayed onto the workpiece, the positional relationship between the workpiece and the light source is such that most of the ultraviolet light emitted from the light source is not irradiated onto the surface of the workpiece. That is, the spray-type processing apparatuses shown in the sixth to eighth embodiments are examples of "positional relationships in which most of the ultraviolet light emitted from the light source is not irradiated onto the surface of the workpiece." Note that, for example, the processing apparatuses of the first to fifth embodiments (FIGS. 1, 2, 6, 9, 10, 11A, and 11B) described below are examples of positional relationships in which the ultraviolet light is irradiated onto the surface of the workpiece.

[0019] The processing gas irradiated with the ultraviolet light may be irradiated with the ultraviolet light again, and the object to be processed may be brought into contact with the processing gas again. Such a processing method can be realized, for example, by using the processing apparatuses shown in the fifth to eighth embodiments (FIGS. 11A, 11B, 12, 13, and 14) described below.

[0020] The processing device of the present invention comprises: a light source that emits ultraviolet light having an emission wavelength of 227 nm or less; a gas supply port connected to a supply source of a raw material gas containing carbon dioxide and having an oxygen concentration of 1000 ppm or less; a water vapor supply unit that adds water vapor to the raw material gas to generate a process gas; Equipped with The light source, the gas supply port, and the water vapor supply unit are arranged so that the ultraviolet light is irradiated onto the processing gas and the object to be processed comes into contact with the processing gas irradiated with the ultraviolet light.

[0021] a processing chamber isolated from the outside and having an area for placing an object to be processed therein; The place where the object to be processed comes into contact with the processing gas may be inside the processing chamber.

[0022] The processing apparatus may have the water vapor supply unit outside the processing chamber. Such processing apparatuses are shown in, for example, first to third embodiments (FIGS. 1, 2, 6, and 9) described below.

[0023] the water vapor supply unit is composed of a pipe through which the raw material gas flows, The piping is made of a material that is permeable to water vapor and may be placed in the atmosphere. Such a treatment device is shown, for example, in a third embodiment (see FIG. 9) to be described later.

[0024] The water vapor supply unit may have a mechanism for bringing the raw material gas into contact with stored water. The mechanism for bringing the raw material gas into contact with stored water may include a mechanism for introducing the raw material gas into water to bubble it, or a mechanism for introducing the raw material gas onto the surface of water or onto the surface of cloth or paper soaked in water to evaporate the water. Treatment devices including such a mechanism for bringing the raw material gas into contact with stored water are shown, for example, in the first, second, and fourth embodiments (see FIGS. 2, 6, and 10) described below.

[0025] The processing apparatus may have the water vapor supply unit inside the processing chamber, such a processing apparatus being shown in, for example, a fourth embodiment (see FIG. 10) to be described later.

[0026] The concentration of carbon dioxide contained in the processing gas may be 5 vol% or more. When the concentration of carbon dioxide is 5 vol% or more, the O(3 P) production efficiency increases.

[0027] The light source may be disposed so that the ultraviolet light is irradiated onto the processing gas present in the atmosphere in which the object to be processed is present.

[0028] The light source, the gas supply port, and the water vapor supply unit may be arranged so as to spray the processing gas irradiated with the ultraviolet light onto the object to be processed.

[0029] The processing system of the present invention includes at least one of the processing devices and at least one of the source gas supply sources connected to the gas supply port. [Effects of the Invention]

[0030] This makes it possible to provide a processing method, processing apparatus, and processing system with improved processing efficiency. [Brief explanation of the drawings]

[0031] [Figure 1] FIG. 2 is a diagram illustrating a part of the processing apparatus according to the first embodiment. [Figure 2] 1 is a diagram showing a processing system including a processing apparatus according to a first embodiment; [Figure 3] 10 is a graph showing the results of a simulation of the amount of decrease in CO concentration due to differences in the amount of water vapor. [Figure 4] FIG. 1 is a diagram showing a processing system used in an experiment. [Figure 5] 1 is a graph showing experimental results of water contact angle. [Figure 6] FIG. 10 is a diagram illustrating a processing system according to a second embodiment. [Figure 7] 10 is a graph showing simulation results of O(3P) concentrations with different carbon dioxide concentrations. [Figure 8A] 10 is a graph showing the simulation results of O(3P) concentration when carbon dioxide is not used. [Figure 8B]10 is a graph showing the simulation results of O(3P) concentration when carbon dioxide is not used. [Figure 9] FIG. 10 is a diagram illustrating a processing system according to a third embodiment. [Figure 10] FIG. 10 is a diagram illustrating a processing system according to a fourth embodiment. [Figure 11A] FIG. 10 is a diagram illustrating a processing system according to a fifth embodiment. [Figure 11B] FIG. 13 is a diagram illustrating a processing system according to a modified example of the fifth embodiment. [Figure 12] FIG. 13 is a diagram illustrating a processing device of a processing system according to a sixth embodiment. [Figure 13] FIG. 13 is a diagram illustrating a processing system according to a seventh embodiment. [Figure 14] FIG. 13 is a diagram illustrating a processing system according to an eighth embodiment. [Figure 15] FIG. 10 is a diagram showing a treatment device additionally provided with a carbon monoxide reduction section. DETAILED DESCRIPTION OF THE INVENTION

[0032] Embodiments of the present invention will be described with reference to the drawings. The drawings disclosed in this specification, except for graphs, are merely schematic illustrations. That is, the dimensional ratios in the drawings do not necessarily correspond to the actual dimensional ratios, and the dimensional ratios between the drawings do not necessarily correspond to the actual dimensional ratios or the number of each component shown in the drawings.

[0033] In the following, each drawing will be described with reference to an XYZ coordinate system as necessary. In this specification, when a direction is expressed and a distinction is made between positive and negative directions, it is described with a positive or negative sign, such as "+X direction" and "-X direction." When a direction is expressed without distinguishing between positive and negative directions, it is simply described as "X direction." In other words, in this specification, when simply referring to "X direction," it includes both the "+X direction" and the "-X direction." The same applies to the Y direction and the Z direction. In the embodiments described below, the direction of gravity is the -Z direction.

[0034] First Embodiment [Processing equipment and processing system] A first embodiment of a processing method, processing apparatus, and processing system will be described with reference to Figures 1 and 2. Figure 1 is a diagram showing a part of a processing apparatus 100 of the first embodiment. Figure 2 is a diagram showing an entire processing system 150 including the processing apparatus 100 and a raw material gas supply source 11.

[0035] The processing apparatus 100 has a light source 1 that emits ultraviolet light L1 having a main emission wavelength of 227 nm or less, and a processing chamber 2 that has the light source 1 therein. The processing chamber 2 has an area therein for placing a workpiece 10, which is an object to be processed. Inside the processing chamber 2, the ultraviolet light L1 emitted from the light source 1 is irradiated onto the workpiece 10. There is no particular limitation on the type of light source used for the light source 1.

[0036] 1 does not show the details of the area where the workpiece 10 is placed, the area where the workpiece 10 is placed may be on a table arranged in the processing chamber 2 or on the inner surface of the housing 3 that constitutes the processing chamber 2. In this embodiment, the light emission surface of the light source 1 is arranged so as to follow the surface of the workpiece 10, and is arranged so that the distance between the light emission surface of the light source 1 and the surface of the workpiece 10 is constant. Also, in this embodiment, the optical axis of the ultraviolet light L1 is arranged so as to be perpendicular to the surface of the workpiece 10, but the optical axis of the ultraviolet light L1 does not have to be perpendicular to the surface of the workpiece 10, and the ultraviolet light L1 may be scattered to the extent that the optical axis cannot be recognized and is incident on the surface of the workpiece 10.

[0037] The ultraviolet light L1 is light having an emission wavelength of 227 nm or less, and in particular, light having a main emission wavelength of 227 nm or less. In this specification, "main emission wavelength of 227 nm or less" means (1) ultraviolet light having at least one peak intensity (maximum intensity) with a wavelength of 227 nm or less, when the emission spectrum of the light source 1 has at least one maximum value, or (2) ultraviolet light having a wavelength component of 227 nm or less that accounts for 30% or more of the total integrated intensity in the emission spectrum of the light source 1. In the case of (1), it is more preferable that the wavelength showing the highest peak intensity is 227 nm or less.

[0038] The ultraviolet light L1 may have an emission wavelength of 227 nm or less and 128 nm or more. If nitrogen gas is present in the light irradiation environment, the ultraviolet light L1 is also irradiated onto the nitrogen gas. Light of 127 nm or less may break the bonds between nitrogen atoms that make up the nitrogen gas, generating nitrogen radicals. If the generated nitrogen radicals combine with oxygen atoms, they may generate NOx, which is undesirable for the environment. Light of 128 nm or more will not generate nitrogen radicals from the nitrogen gas, thereby suppressing the generation of NOx when nitrogen gas is present in the light irradiation environment.

[0039] The interior of the processing chamber 2 is isolated from the outside of the processing chamber 2 by a housing 3. Inside the housing 3, there are a location (not shown) for arranging the light source 1 and the workpiece 10, and a light-transmitting wall 4 between the light source 1 and the workpiece 10, which separates the space where the light source 1 is arranged from the space where the workpiece 10 is arranged. In other words, the processing chamber 2 is separated by the light-transmitting wall 4 into the space where the light source 1 is arranged and the space where the workpiece 10 is arranged. The light-transmitting wall 4 transmits light of the main emission wavelength of the light source 1 (in this embodiment, light of 227 nm or less).

[0040] The space in which the light source 1 is disposed is filled with a gas (for example, an inert gas such as nitrogen) that does not easily absorb ultraviolet light L1. Although not shown in FIG. 1, a gas supply port for supplying gas and a gas exhaust port for exhausting gas from the space in which the light source 1 is disposed may be provided adjacent to the space in which the light source 1 is disposed. Both the gas supply port and the gas exhaust port are holes provided in the housing 3. Continuously supplying an inert gas to the space in which the light source 1 is disposed also has the effect of cooling the light source 1.

[0041] The processing apparatus 100 may have a structure that does not have a light-transmitting wall 4 inside the processing chamber 2. Furthermore, the space in which the light source 1 is placed may be a vacuum (reduced pressure) environment. In this embodiment, the light source 1 is placed inside the processing chamber 2, but the light source 1 may also be placed outside the processing chamber 2. When the light source 1 is placed outside the processing chamber 2, it is sufficient that a part of the housing 3 is made of a light-transmitting member so that the light source 1 can emit light into the processing chamber 2.

[0042] The processing chamber 2 is provided with a gas supply port 5 and a gas exhaust port 6 adjacent to the space in which the workpiece 10 is placed. The gas supply port 5 and the gas exhaust port 6 are both gas circulation holes provided in the housing 3. The gas supply port 5 is connected to a raw material gas supply source (not shown in FIG. 1). The gas exhaust port 6 is connected to a gas suction source (not shown). The gas supply port 5 and the gas exhaust port 6 are arranged to sandwich the space above the workpiece 10, so that the processing gas G1 supplied to the processing chamber 2 comes into contact with the surface of the workpiece 10 to be processed.

[0043] The processing gas G1 supplied to the processing chamber 2 contains carbon dioxide. The concentration of carbon dioxide in the processing gas G1 is not particularly limited, but it is preferable that the concentration of carbon dioxide in the processing gas G1 be 5 vol% or more. The reason why 5 vol% or more is preferable will be described later. A carbon dioxide concentration meter may be placed in the processing chamber 2 or upstream of the gas supply port 5.

[0044] A raw material gas containing carbon dioxide is supplied from a raw material gas supply source 11. In this embodiment, the raw material gas supply source 11 is a carbon dioxide gas cylinder in which high-purity (99 vol% or more) carbon dioxide is sealed under high pressure, but the raw material gas supply source 11 may be provided by means other than a cylinder.

[0045] The processing gas G1 supplied to the processing chamber 2 contains almost no oxygen gas. The oxygen concentration in the processing gas G1 is 1000 ppm or less. If the oxygen concentration is low, O( 3 P), the number of atomic oxygen O( 3 P) can be used to modify or clean the surface of the object to be treated.

[0046] The processing gas G1 supplied to the processing chamber 2 also contains water vapor. The water vapor concentration in the processing gas G1 is preferably 5 ppm or more and 30,000 ppm or less. The reason why the water vapor concentration is preferably 5 ppm or more and 30,000 ppm or less will be described later.

[0047] The water vapor supply unit 15 (see FIG. 2) included in the processing apparatus 100 will be described. The water vapor supply unit 15 of this embodiment is disposed outside the processing chamber 2. The water vapor supply unit 15 is provided midway along a gas flow path connecting the raw material gas supply source 11 and the gas supply port 5 of the processing apparatus 100. The raw material gas supplied from the raw material gas supply source 11 passes through the water vapor supply unit 15, thereby adding water vapor. The raw material gas with added water vapor is then supplied from the gas supply port 5 as a processing gas.

[0048] In this embodiment, the water vapor supply unit 15 employs a bubbling method in which the source gas is sprayed into water stored in a container. When the source gas is sprayed into the water to form bubbling, the water evaporates. As a result, water vapor is added to the source gas.

[0049] The processing system 150 has a flow rate control valve 12 that adjusts the flow rate of the source gas supplied from the source gas supply source 11, and a flow meter 13 that detects the flow rate. The amount of water vapor to be added can be adjusted by the flow rate of the source gas to be bubbled. The amount of water vapor may also be adjusted by controlling the temperature of the water stored in the container with a heater (not shown) or the like.

[0050] In addition to water vapor, mist-like water (floating water droplets) may also be mixed into the processing apparatus 100. Large particle sizes of mist-like water may block the transmission of ultraviolet light and make it difficult to generate oxygen radicals. The amount of mist-like water may be reduced from the processing gas. To reduce the amount of water, for example, a filter that traps water droplets may be placed between the water vapor supply unit 15 and the gas supply port 5.

[0051] In this embodiment, the water vapor supply unit 15 is disposed outside the processing chamber 2, but this is not limiting. As will be described later in another embodiment, the water vapor supply unit may be provided inside the processing chamber 2. Furthermore, the source gas supply source 11 containing carbon dioxide may itself inherently contain water vapor. In other words, the source gas supply source 11 may be a processing gas supply source containing not only carbon dioxide but also water vapor.

[0052] Using the above-described processing system, ultraviolet light L1 in a wavelength range is irradiated onto the processing gas G1 that is in contact with the workpiece 10. Carbon dioxide (hereinafter, sometimes referred to as "CO2") contained in the processing gas G1 is converted into ground-state atomic oxygen O ( 3 P) is generated and O( 3 P) processes the surface of the workpiece 10.

[0053] In this embodiment, atomic oxygen is generated mainly using CO2 instead of oxygen gas (hereinafter, sometimes referred to as "O2"). Below, the reason for using a gas containing CO2 as the process gas G1 will be explained by comparing the case where UV light L1 is irradiated onto CO2 with the case where UV light L1 is irradiated onto O2.

[0054] [When irradiating oxygen gas with ultraviolet light] Unlike the present embodiment, consider a case where ultraviolet light is irradiated onto a process gas containing a large amount of O. When the wavelength λ of the ultraviolet light L1 is longer than 175 nm and equal to or shorter than 242 nm, the photodecomposition of O2 when the energy (hν) of the ultraviolet light L1 is applied to O2 is shown in Equation (1). O2+ hν → O( 3 P) + O( 3 P) (1) As shown in equation (1), photolysis produces ground-state atomic oxygen O( 3 P) is obtained.

[0055] When the wavelength λ of ultraviolet light L1 is 175 nm or less, the photodecomposition of O2 when the energy (hν) of ultraviolet light L1 is given to O2 is shown in equation (2). O2+ hν → O( 1 D) + O( 3 P) (2) (2) 1 D) is excited atomic oxygen. However, as shown in the following equation (3), energy is lost through collisions with surrounding molecules M, resulting in O( 1 D) has a short lifetime. The excited state of atomic oxygen O( 1 D) immediately converts to ground state atomic oxygen, O( 3 It is often converted to P. O( 1 D)+M → O( 3 P)+M (3) Ultimately, even when the wavelength λ of the ultraviolet light L1 is 175 nm or less, what is ultimately obtained is mainly ground state atomic oxygen O( 3 P).

[0056] As shown in equations (1), (2), and (3), when ultraviolet light L1 is irradiated onto the workpiece 10 in contact with O2, O( 3 P) is generated. And the generated O( 3P) often reacts with O2 molecules in the atmosphere to produce ozone (O3). Generally, ozone has a strong oxidizing power, but O( 3 Compared to O(P), the speed of surface modification and cleaning of the workpiece 10 is slow. Therefore, to improve the efficiency, it is necessary to irradiate the workpiece with ultraviolet light again and achieve O( 3 P), and there was room for improvement in terms of efficiency.

[0057] [When carbon dioxide gas is irradiated with ultraviolet light] Consider the case where ultraviolet light is irradiated onto a process gas containing a large amount of CO, as in this embodiment. When the wavelength λ of the ultraviolet light is longer than 166 nm and shorter than 227 nm, the photodecomposition of CO when the energy (hν) of the ultraviolet light is applied to it is shown in Equation (4). CO2+hν → CO+O( 3 P) (4) As shown in equation (4), photolysis produces ground-state atomic oxygen O( 3 P) and carbon monoxide (hereinafter sometimes referred to as "CO").

[0058] When the wavelength λ of ultraviolet light is 166 nm or less, the photodecomposition of CO2 when ultraviolet light energy hν is given to CO2 is shown in equation (5). CO2+hν → CO+O( 1 D) (5) (5) 1 D) is excited atomic oxygen. However, as shown in equation (3), energy is lost through collisions with surrounding molecules M, resulting in excited atomic oxygen O( 1 D) is the atomic oxygen in the ground state, O( 3 P). Equation (3) is shown below again. O( 1 D)+M → O( 3 P)+M (3) Ultimately, even when the wavelength λ of ultraviolet light is 166 nm or less, what is ultimately obtained is mainly ground state atomic oxygen O( 3 P).

[0059] As shown in equations (4), (5) and (3), UV light converts CO2 to O( 3 P) is generated. However, the generated O( 3 P) is hardly lost by reacting with CO2 in the atmosphere or carbon monoxide produced by photolysis. This is different from an atmosphere containing O2. Therefore, the generated O( 3 P) can be efficiently used for surface modification and cleaning of the workpiece 10.

[0060] A secondary effect of irradiating ultraviolet light in a CO2 atmosphere will now be explained. This is that CO2 is less easily absorbed than O2, and high-intensity ultraviolet light can be irradiated onto the workpiece 10. For example, the absorption cross section of O2 for vacuum ultraviolet light with a wavelength of 172 nm is approximately 6 x 10 -19 cm 2 whereas the absorption cross section of CO2 is about 1×10 -20 cm 2 Because the absorption cross section of O2 is large, even in an air atmosphere containing only 21% O2, the reach of the ultraviolet light L1 (the distance at which the illuminance is 1 / e, where e is the base of the natural logarithm) is short, at about 4 mm. In contrast, even in a highly concentrated atmosphere such as a 100% CO2 atmosphere, the reach of vacuum ultraviolet light can be secured as long as about 4 cm. Therefore, the constraints on the distance between the light source 1 and the workpiece 10 are reduced, and, for example, surface modification and cleaning processes can be performed on workpieces with uneven surfaces.

[0061] For optical processing that does not rely on O2, CO2 is essential. However, the main component of the processing gas G1 does not necessarily have to be CO2. The main component of the processing gas G1 may also be an inert gas such as nitrogen gas. The inert gas enables optical processing when mixed with CO2. When the processing gas G1 contains an inert gas, it is recommended to use light in a wavelength range that does not decompose the inert gas. Among inert gases, nitrogen gas, in particular, has the same low attenuation of ultraviolet light as carbon dioxide, which offers advantages such as a long reach of vacuum ultraviolet light, low cost, and easy availability. As mentioned above, when the processing gas G1 contains nitrogen gas as an inert gas, it is recommended to use light of 128 nm or longer to prevent the nitrogen gas from being decomposed by ultraviolet light.

[0062] [Use of process gas containing water vapor] The processing gas of this embodiment contains water vapor. The effectiveness of a processing gas containing water vapor will be explained below. As described in the section "When carbon dioxide gas is irradiated with ultraviolet light," photolysis of CO2 generates CO. Since CO2 is harmful to living organisms, it is desirable to reduce the CO2 concentration and discharge the gas from the processing apparatus 100. Therefore, the use of a processing gas containing water vapor was devised.

[0063] Equation (6) shows the photolysis of water vapor (H2O) when it is given the energy (hν) of ultraviolet light L1. H2O+hν → OH+H (6)

[0064] The OH radicals generated in equation (6) oxidize CO and convert it to CO2, as shown in equation (7). CO + OH → CO2 + H (7) When the generated CO2 is irradiated with ultraviolet light, CO is generated again (see the above formulas (4) and (5)).

[0065] By the way, according to the above formula (4) or the above formula (5) and the above formula (3), a large amount of O( 3 P) is generated. Two O( 3P) combine with each other to produce O2. This is shown in equation (8). M in equation (8) represents the molecules present in the surrounding area. O( 3 P)+O( 3 P) + M → O2 + M (8)

[0066] Second, O( 3 Ozone (O3) is produced when P reacts with O2. M in equation (9) represents the molecules present in the surrounding area. O( 3 P) + O2 + M → O3 + M (9)

[0067] Thus, the environment irradiated with light may contain ozone derived from CO2. Ozone oxidizes H radicals produced by the photolysis of water vapor (see equation (6)) to produce OH radicals, which are shown in equation (10). H + O3 → OH + O2 (10)

[0068] The OH radicals generated by equation (10) also oxidize CO and convert it to CO2, as shown by equation (7). The H radicals obtained by equation (8) again generate OH radicals by equation (10). In other words, if there are even a small amount of H radicals in the ozone gas atmosphere, a cyclic reaction occurs in which CO is oxidized and converted to CO2. As a result, the supply of even a small amount of water vapor can trigger the generation of a large amount of OH radicals, promoting the oxidation reaction of CO. OH radicals can also promote surface modification of the workpiece 10.

[0069] As described above, when the treatment gas contains water vapor, CO generated by photolysis of carbon dioxide gas is converted into CO2, thereby reducing the CO concentration that is harmful to living organisms.

[0070] [Water vapor volume simulation] The effect of adding water vapor to the source gas was verified through simulation. The simulation conditions are as follows: The process gas was passed through a light irradiation space at room temperature (298K), and light from a xenon excimer lamp with a main emission wavelength of 172 nm was irradiated at 30 mW / cm. 2 The light is irradiated at an illuminance of 100 ppm. The light irradiation space is assumed to be a closed space in which gas, including the processing gas, does not flow in or out of the processing chamber. The processing gas is assumed to be filled with a source gas containing 100 vol% CO2 to which a specified amount of water vapor has been added. As a comparative example, a processing gas consisting of only the source gas without the addition of water vapor is set. Specifically, the change in CO concentration with respect to the light irradiation time is simulated for processing gases with four water vapor concentrations set to 500 ppm, 50 ppm, 5 ppm, and 0 ppm. The pressure and temperature are assumed to be 1 atmosphere and 298 K (25°C) in all cases.

[0071] Figure 3 shows the simulation results for four types of process gases. In the graph shown in Figure 3, the horizontal axis represents the light irradiation time (unit: seconds), and the vertical axis represents the CO concentration (unit: ppm) in the process chamber 2. Curves C1 to C4 represent the following process gases. Curve C1: Treated gas with a water vapor concentration of 500 ppm Curve C2: Treated gas with a water vapor concentration of 50 ppm Curve C3: Treated gas with a water vapor concentration of 5 ppm Curve C4: Process gas with a water vapor concentration of 0 ppm (no water vapor added, consisting only of raw material gas)

[0072] As shown by curve C4, in the case of a process gas that does not contain water vapor, CO2 is decomposed as the irradiation time increases, and the CO2 concentration in the light-irradiated space increases. After 1000 seconds, the CO2 concentration in the closed space is approximately 7 x 10 5 As shown in curve C3, in the case of a treatment gas containing a water vapor concentration of 5 ppm, the CO concentration in the closed space reaches approximately 3 × 10 after 1000 seconds. 5ppm (30 vol%). This means that the presence of water vapor reduces the CO concentration by more than half. As shown in curve C2, in the case of treatment gas containing 50 ppm water vapor, the CO concentration remains at 0.5 x 10 even after 1000 seconds. 5 As shown in curve C1, in the case of a processing gas containing a water vapor concentration of 500 ppm, even after 1000 seconds, the water vapor concentration is 0.1 × 10 ppm, which is even lower than the case of 50 ppm. 5 The CO concentration is less than ppm.

[0073] The simulation results in Figure 3 show that the CO concentration tends to decrease as the water vapor concentration increases. This simulation is based on the premise of a closed space where gases, including the treatment gas, do not flow in or out along the way. However, even when light is irradiated in a space where gases flow in and out along the way, the CO concentration does not become as high as in Figure 4, but the tendency for the CO concentration to decrease as the water vapor concentration increases remains unchanged.

[0074] The water vapor concentration is preferably 50 ppm or higher, more preferably higher than 100 ppm, and even more preferably higher than 500 ppm. However, although the CO2 concentration decreases as the water vapor concentration increases, the degree of decrease in CO2 concentration decreases as the water vapor concentration increases. Furthermore, the saturated water vapor amount in a space filled with CO2 is about 30,000 ppm, and if water vapor is added in excess of the saturated water vapor amount, condensation may occur, affecting light transmission. Therefore, the water vapor concentration should be 30,000 ppm or less.

[0075] [Effect of water vapor on light treatment] An experiment was conducted to investigate the effect of water vapor on photoprocessing. Figure 4 shows the processing system 250 used in the experiment. The processing system 250 will now be described in detail. The processing device 200 has a light source 1, a workpiece 10 arranged at a distance d1 (d1 = 1 (mm)) from the light source 1, and a processing chamber 2 in which the light source 1 and the workpiece 10 are arranged without a translucent wall 4 being arranged. The light source 1 is a xenon excimer lamp that emits ultraviolet light L1 with a main emission wavelength of 172 nm. The illuminance at the lamp surface is 30 mW / cm 2 is. The raw material gas supply source 11 supplies CO2 at 99.9 vol% or more. The water vapor supply unit 15 adds approximately 20,000 ppm of water vapor to the raw material gas by bubbling. The workpiece 10 is a substrate made of polypropylene resin (PP).

[0076] The surface of the PP workpiece 10 is hydrophobic, but by irradiating it with ultraviolet light L1 in a CO2 atmosphere, hydrophilic functional groups such as OH groups, C=O groups, or COOH groups are added, modifying the surface to make it hydrophilic. In other words, when the workpiece 10 is irradiated with ultraviolet light L1 in a CO2 atmosphere, the water contact angle of the surface of the workpiece 10 decreases.

[0077] FIG. 5 shows the change in water contact angle with irradiation time. The water contact angle of the workpiece 10 at an irradiation time of 0 seconds represents the water contact angle of the untreated workpiece 10. The points on curve C5 represent the water contact angles of the surface of the workpiece 10 irradiated with ultraviolet light L1 for 30 seconds or 120 seconds in a treatment gas atmosphere containing no water vapor. In contrast, the points on curve C6 represent the water contact angles of the surface of the workpiece 10 irradiated with ultraviolet light L1 for 30 seconds or 120 seconds in a treatment gas atmosphere containing approximately 20,000 ppm of water vapor, as described above. All conditions are the same except for whether or not water vapor is added.

[0078] The water contact angle was measured using a contact angle meter DMs-401 manufactured by Kyowa Interface Science Co., Ltd. The contact angle was calculated from the measurement results of the contact angle meter using an ellipse curve fitting method. This contact angle calculation was performed at three locations on the surface of the same workpiece 10. The water contact angles measured at the three locations were averaged, and this average value was determined to be the final water contact angle. Other measurement conditions for the water contact angle were in accordance with JIS R 3257:1999 "Test method for wettability of substrate glass surfaces."

[0079] It was confirmed from Figure 5 that the hydrophilic treatment was carried out without any problems even when irradiating with ultraviolet light L1 in a process gas atmosphere containing water vapor.In fact, the results showed that irradiating with ultraviolet light L1 in a process gas atmosphere containing water vapor resulted in more hydrophilic treatment in the same amount of time than irradiating with ultraviolet light L1 in a process gas atmosphere without water vapor.

[0080] The reason why surface modification is more advanced when irradiated with light under a process gas atmosphere containing water vapor is presumably due to the occurrence of the cycle reaction triggered by the supply of water vapor, as described above. It is believed that the large amount of OH radicals generated during the cycle reaction not only contributes to the oxidation reaction of CO but also to the surface treatment of the workpiece 10. In this way, using a process gas containing water vapor not only has the effect of reducing harmful CO, but also has the effect of improving processing efficiency.

[0081] Second Embodiment The second embodiment will be described with reference to FIG. 6. The following description will focus on features that are different from the first embodiment. Points not described in the second embodiment can be implemented in the same way as the first embodiment. The same applies to the third and subsequent embodiments.

[0082] [Processing System] In the processing system 350 of the second embodiment, a source gas supply source 11 and a second source gas supply source 21 are connected to the processing device 300. The processing device 300 has a housing 3 that includes a second gas supply port 25 connected to the second source gas supply source 21, separate from the gas supply port 5 connected to the source gas supply source 11. However, in this embodiment, the second source gas itself is an inert gas that does not directly contribute to light irradiation or processing. The inert gas functions as a carrier gas for water vapor. Specifically, the inert gas supplied from the second source gas supply source 21 passes through the water vapor supply unit 15, thereby supplying the inert gas containing water vapor into the processing chamber 2. In the processing chamber 2, CO2 supplied from the gas supply port 5 mixes with the inert gas containing water vapor. In this embodiment, the inert gas supplied from the second source gas supply source 21 is nitrogen gas. The purity of the nitrogen gas is 99.9 vol% or higher. The flow rate of the nitrogen gas is adjusted by a flow control valve 22 and a flow meter 23. In this way, the source gas excluding water vapor in the process gas does not necessarily have to be composed only of CO2, and the source gas may contain an inert gas. Furthermore, the source gas supply source 11 itself may supply carbon dioxide containing an inert gas as the source gas.

[0083] [Carbon dioxide concentration simulation] A simulation was conducted to determine the preferred range of CO2 concentration in the irradiation atmosphere. Figure 7 shows the results of a CO2 concentration simulation under a light irradiation atmosphere containing carbon dioxide gas and nitrogen gas. However, the calculation was performed under the condition that the light irradiation atmosphere also contained 1000 ppm of oxygen gas. The CO2 concentration represents the proportion of carbon dioxide gas in a mixed gas composed of carbon dioxide gas and nitrogen gas. Strictly speaking, at any CO2 concentration, the CO2 concentration is defined as the proportion of carbon dioxide gas in a mixed gas composed of carbon dioxide gas, nitrogen gas, and oxygen gas. However, because 1000 ppm of oxygen gas in a mixed gas is a small amount compared to 1%, in practice, the proportion of carbon dioxide gas in a gas composed of carbon dioxide gas and nitrogen gas can be referred to as the CO2 concentration without considering the small amount of oxygen gas.

[0084] The O( 3 P) Concentration (1cm 3 Hit O( 3 The result is the number of O( 3 P) The E+N in the concentration value represents 10 to the Nth power. For example, 1.00E+13 is 1.00 x 10 13 Represents.

[0085] The simulation conditions are as follows: It is assumed that the light source 1 is located at a distance of d1 = 1 cm from the surface of the workpiece 10. The light source 1 is a xenon excimer lamp (main emission wavelength is 172 nm, illuminance at d1 = 0 is 30 mW / cm 2 ) is used. d1 = 1 cm. The pressure is 1 atmosphere and the temperature is 300 K (27 °C).

[0086] As can be seen in Figure 7, the higher the CO2 concentration, the more O( 3 P) concentration increases. O( 3 Since a higher P concentration promotes surface treatment, a higher CO2 concentration is preferable. However, the maximum O( 3 P) concentration is 2.5 x 10 12 pieces / cm 3 Considering that this has been confirmed in another experiment described later, O( 3 P) concentration is 3.0 × 10 12 pieces / cm 3 In a CO2 atmosphere with a CO2 concentration of 5 vol% or more, even if the O2 concentration is changed, the O( 3 Therefore, in order to enjoy the advantages of using a gas containing CO2 as the processing gas, the CO2 concentration contained in the processing gas should be 5 vol% or more.

[0087] In the above simulation, the distance d1 from the light source 1 to the surface of the workpiece 10 is set to 1 cm. However, even if the distance d1 from the light source 1 to the surface of the workpiece 10 is 0.1 cm, the maximum O( 3 In addition, the above simulation was performed under the condition that the O2 concentration was set to 1000 ppm, but even when the O2 concentration is lower than 1000 ppm, the higher the CO2 concentration, the greater the O( 3 P) concentration increases, the situation remains unchanged.

[0088] [Maximum O( 3 P) Concentration confirmation experiment] The maximum O( 3 P) concentration is 2.5 x 10 12 pieces / cm 3 We will now explain the experiments that confirmed this.

[0089] Figure 8A shows the O( 3 The horizontal axis shows the oxygen gas concentration in the mixed gas of oxygen and nitrogen gas. 3 P) concentration is 1 cm 3 Hit O( 3 P) is expressed as the number of O( 3 The notation for P) concentration is as described above.

[0090] The simulation conditions are as follows: It is assumed that the light source 1 is located at a distance d1=1 cm from the surface of the workpiece 10. The processing device is assumed to be the processing device 200 shown in FIG. 4. The light source 1 is a xenon excimer lamp (main emission wavelength is 172 nm, illuminance at d1=0 is 30 mW / cm 2 ) is used. d1 = 1 cm. The pressure is 1 atmosphere and the temperature is 300 K (27 °C).

[0091] As shown in FIG. 8A, the highest O( 3 P) Concentration (2.5×10 12 pieces / cm 3 ) and even if it increases or decreases from 1000 ppm, O( 3 The reason for this is that the O( 3 If the amount of O(P) becomes small and the oxygen gas concentration is too high, the light is absorbed by the oxygen gas in the atmosphere, the amount of light reaching the surface of the workpiece (i.e., the illuminance on the surface of the workpiece) decreases, and the amount of O( 3 P) is small, and as mentioned above, the generated O( 3 This is because P reacts with oxygen gas to form ozone (O3).

[0092] As in Figure 8A, Figure 8B shows the O( 3 8A, it is assumed that the light source 1 is located at a distance d1 = 0.1 cm from the surface of the workpiece 10. The other simulation conditions are the same as those in FIG. 8A.

[0093] As shown in FIG. 8B, even when the distance from the light source was changed, the largest amount of O( 3 P) Concentration (2.5×10 12 pieces / cm 3 ) was found to be reached.

[0094] 8A and 8B show that the maximum O( 3 P) concentration is 2.5 x 10 regardless of the distance from the light source. 12 pieces / cm 3 When carbon dioxide gas is used, the maximum O( 3 P) concentration is 2.5 x 10 12 pieces / cm3 , which exceeds O( 3 It is preferred to produce P).

[0095] Third Embodiment The third embodiment will be described with reference to Fig. 9. A processing system 450 of the third embodiment uses the same processing apparatus 100 as the processing apparatus 100 of the first embodiment. The difference from the first embodiment is a water vapor supply unit 35 disposed between the source gas supply source 11 and the gas supply port 5.

[0096] The water vapor supply unit 35 in this embodiment is composed of a resin tube through which the source gas flows. The resin constituting the resin tube has fine pores, allowing water vapor to pass through. When a water vapor-permeable resin tube is placed in an atmospheric environment, a small amount of water vapor from the atmosphere penetrates the resin tube, and the penetrated water vapor is transported to the processing device 100 along with the source gas. Using a resin tube for the water vapor supply unit 35 is particularly suitable for small amounts of water vapor, such as when the target water vapor content is 1000 ppm or less, more preferably 100 ppm or less. The amount of water vapor can be precisely adjusted by selecting the resin tube material, changing the resin tube length or thickness, or changing the temperature and humidity of the atmospheric environment. Materials for the resin tube include polyethylene, urethane, nylon, fluororesin, polyolefin, and polyvinyl chloride, without any particular limitations. Note that metal piping may be used in areas where water vapor penetration from the atmosphere is undesirable. Even if the resin tube is permeable to atmospheric nitrogen as well as water vapor, it does not pose a problem because the carbon dioxide concentration does not decrease significantly. Also, even if atmospheric oxygen is permeable, it does not pose a problem because the oxygen concentration does not exceed 1000 ppm as a result of the oxygen permeation.

[0097] <Fourth embodiment> A fourth embodiment will be described with reference to FIG. 10 . A treatment system 550 of the fourth embodiment includes a treatment device 500 having a water vapor supply unit 55 inside the treatment chamber 2. The water vapor supply unit 55 is a cloth or paper soaked in water (hereinafter, only “cloth” will be described as the object to be soaked in water, but in the following description, the object to be soaked in water may also be paper). Water vapor is added to the gas inside the treatment chamber 2 as water evaporates from the cloth. In the treatment device 500 of this embodiment, when water is lost from the cloth due to evaporation, water is replenished from a water supply source outside the treatment chamber 2. However, the water supply source inside the treatment chamber 2 is not necessarily required. As the water evaporates and the cloth dries, it may be replaced with a water-soaked cloth as needed. Furthermore, gas ejected from the gas supply port 5 may be directed toward the cloth of the water vapor supply unit 55 to promote water evaporation. Water vapor supply units (15, 35, 55) may be provided both inside and outside the treatment chamber 2.

[0098] Fifth Embodiment The fifth embodiment will be described with reference to FIG. 11A. A processing system 650 of the fifth embodiment has a return flow path 31 that returns gas exhausted from a processing chamber 2 to an upstream side of the processing chamber 2. The return flow path 31 is connected to the main flow path by a flow path switching valve (32, 33). Although not shown in FIG. 11A, a pump for circulating gas may be provided in the return flow path 31. The processing device 100 used in the processing system 650 is the same as the processing device 100 of the first embodiment. Although FIG. 11A does not show the upstream side of the flow path switching valve 32, the same structure as in the other embodiments can be applied to the upstream side.

[0099] In one pass through the processing chamber 2, all of the carbon dioxide gas contained in the processing gas supplied to the processing chamber 2 is converted into CO and O( 3Since CO generated by photolysis is converted back into CO2 by reaction with OH radicals, the processing gas discharged from the processing chamber 2 still contains a large amount of carbon dioxide gas. Therefore, the processing gas discharged from the processing chamber 2 is returned to the upstream of the processing chamber 2 using the return flow path 31, and the processing gas is reused. This allows for efficient use of carbon dioxide and reduces costs. The processing gas containing carbon dioxide passes through the processing chamber 2 a predetermined number of times to convert it back into O( 3 The flow path switching valves (31, 32) may be controlled to repeatedly generate and then discharge the process gas (P). The flow path switching valves (31, 32) may be flow path adjusting valves whose opening degree is adjustable. By using the flow path adjusting valves, the flow rate ratio of unused process gas to used process gas can be controlled.

[0100] A modified example of the fifth embodiment is shown in Fig. 11B. The processing system 660 of this modified example has an additional water vapor supply unit 36 ​​in the return flow path 31. The gas flowing through the return flow path 31 is bubbled in water to increase the amount of water vapor in the reused processing gas. Although the additional water vapor supply unit 36 ​​of this embodiment employs a bubbling method, water vapor may be added by other methods.

[0101] Sixth Embodiment A processing system according to the sixth embodiment will be described with reference to FIG. 12. The processing system according to this embodiment is characterized by the processing device. The processing device 700 is a type of processing device that sprays a processing gas irradiated with light toward the surface of the workpiece 10. The processing device 700 includes a gas flow path 8 inside the processing chamber 2 through which the processing gas G1 flows. The gas flow path 8 is formed along the light emission region of the light source 1, and the light source 1 and the gas flow path 8 are arranged so that the gas flow path 8 overlaps with the light emission region. An outlet 45 of the gas flow path 8 is arranged opposite the workpiece 10. This allows atomic oxygen O( 3 The processing gas G1 containing P is ejected from the outlet 45 of the gas flow path 8 and sprayed toward the workpiece 10. In this way, the workpiece 10 is processed.

[0102] The workpiece 10 may be placed on a movable stage and processed by scanning the workpiece 10 under the outlet 45 from which the processing gas G1 is ejected. Alternatively, the outlet 45 may be scanned while the workpiece 10 is fixed, or both the workpiece 10 and the outlet 45 may be scanned. Such a mechanism for moving the workpiece 10 relative to the outlet 45 is not limited to this embodiment, but can also be applied to the other embodiments described above and other embodiments described below.

[0103] Seventh Embodiment A processing system according to the seventh embodiment will be described with reference to FIG. 13. The processing system according to this embodiment includes the processing apparatus 700 shown in the sixth embodiment. The processing gas discharged from the processing apparatus 700 shown in the sixth embodiment can be reused. The processing gas discharged from the processing chamber 2 is returned upstream of the processing chamber 2 using the return flow path 31, thereby reusing the processing gas. This allows for efficient use of carbon dioxide and reduces costs. Although not shown in FIG. 13, a water vapor supply unit may be further provided in the return flow path 31, as shown in the modified example of the fifth embodiment (FIG. 11B).

[0104] Eighth Embodiment Referring to FIG. 14, a processing apparatus according to an eighth embodiment is shown. Unlike the processing apparatus 700 according to the sixth embodiment, the processing apparatus 800 according to the eighth embodiment circulates and reuses the source gas within the processing chamber 2. The processing apparatus 800 includes a suction port 51 upstream of the light source 1 for sucking gas from the processing chamber 2, and a suction fan 52. The processing gas G1 irradiated with ultraviolet light is sucked in, and the sucked processing gas G1 is again irradiated with ultraviolet light, and the irradiated processing gas G1 is again brought into contact with the workpiece 10. As shown in FIG. 10, a water vapor supply unit may be disposed within the processing chamber 2, as in the fourth embodiment.

[0105] While the processing gas G1 is circulated in the processing chamber 2 for a predetermined time, the supply of the processing gas G1 from the gas supply port 5 and the exhaust of the processing gas G1 from the gas exhaust port 6 may be stopped or continued.

[0106] The present invention is not limited to the above-described embodiments and their modifications, and various modifications and improvements can be made to the above-described embodiments and their modifications as appropriate, without departing from the spirit of the present invention.

[0107] A modified example of the treatment device will be described with reference to FIG. 15 . The treatment device 900 shown in FIG. 15 additionally includes a carbon monoxide reduction unit 9. The treatment device 900 originally reduces CO by using steam. However, in consideration of cases where CO reduction by steam is insufficient, a carbon monoxide reduction unit 9 may be additionally provided downstream of the gas outlet 6. The carbon monoxide reduction unit 9 may adsorb carbon monoxide by an adsorption method. In the adsorption method, the carbon monoxide reduction unit 9 includes an adsorbent material for adsorbing carbon monoxide. The adsorbent material may be composed of activated carbon, zeolite, a metal, or a metal complex. The carbon monoxide reduction unit 9 may convert carbon monoxide to carbon dioxide by an incineration method or a catalytic oxidation method. In the incineration method, the carbon monoxide reduction unit 9 includes a combustion furnace. In the catalytic oxidation method, a carbon monoxide oxidizing fluid, such as sulfur dioxide gas, may be introduced into the carbon monoxide reduction unit 9 and brought into contact with the carbon monoxide gas.

[0108] Another modified embodiment of the processing apparatus will now be described. The processing apparatus of each of the above-described embodiments includes a processing chamber 2 to isolate the processing space from the atmospheric space. However, since isolating the processing space from the atmospheric space is not necessarily required in all situations, the processing chamber 2 is not necessarily required in the processing apparatus of each of the above-described embodiments. The processing apparatus of each of the above-described embodiments does not necessarily have to include the processing chamber 2. [Explanation of symbols]

[0109] 1:Light source 2: Processing chamber 3: Housing 4: Translucent wall 5: Gas supply port 6: Gas outlet 8: Gas flow path 9: Carbon monoxide reduction unit 10: Work 11: Raw material gas supply source 12, 22: Flow control valve 13,23 :Flow meter 15, 35, 55: Steam supply section 21: Second raw material gas supply source 25: Second gas supply port 31: Return flow path 32: Flow path switching valve 36: Further steam supply 45: Outlet 51: Suction port 52: Suction fan 100, 200, 300, 500, 700, 800, 900: Processing unit 150, 250, 350, 450, 550, 650, 660: Processing System G1: Processing gas L1: Ultraviolet light

Claims

1. Irradiating a treatment gas containing carbon dioxide, having an oxygen concentration of 1000 ppm or less, and a water vapor concentration of 5 ppm or more and 30000 ppm or less, with ultraviolet light having an emission wavelength of 227 nm or less; The processing method includes contacting the processing gas irradiated with the ultraviolet light with the object to process the object.

2. 2. The processing method according to claim 1, wherein the concentration of carbon dioxide contained in the processing gas is 5 vol % or more.

3. 2. The processing method according to claim 1, wherein the processing gas is generated by adding water vapor to a raw material gas containing carbon dioxide and having an oxygen concentration of 1000 ppm or less.

4. 4. The processing method according to claim 1, wherein the water vapor concentration in the processing gas is 50 ppm or more.

5. 4. The processing method according to claim 1, wherein the processing gas is brought into contact with the object to be processed in a processing chamber isolated from an atmospheric space.

6. 4. The processing method according to claim 1, wherein the ultraviolet light is irradiated onto the processing gas present in an atmosphere in which the object to be processed is present.

7. 4. The processing method according to claim 1, wherein the processing gas irradiated with the ultraviolet light is sprayed onto the object to be processed.

8. 2. The processing method according to claim 1, wherein the processing gas irradiated with the ultraviolet light is again irradiated with the ultraviolet light, and the object to be processed is again brought into contact with the ultraviolet light.

9. a light source that emits ultraviolet light having an emission wavelength of 227 nm or less; a gas supply port connected to a source of a raw material gas containing carbon dioxide and having an oxygen concentration of 1000 ppm or less; a water vapor supply unit that adds water vapor to the raw material gas supplied from the raw material gas supply source to generate a process gas; Equipped with a processing apparatus, characterized in that the light source, the gas supply port, and the water vapor supply unit are arranged so that the processing gas is irradiated with the ultraviolet light and the workpiece comes into contact with the processing gas irradiated with the ultraviolet light.

10. a processing chamber isolated from the outside and having an area for placing an object to be processed therein; 10. The processing apparatus according to claim 9, wherein the object to be processed comes into contact with the processing gas inside the processing chamber.

11. 11. The processing apparatus of claim 10, wherein the water vapor supply is external to the processing chamber.

12. the water vapor supply unit is composed of a pipe through which the raw material gas flows, The treatment apparatus according to claim 9, wherein the piping is made of a material that is permeable to water vapor and is disposed in the atmosphere.

13. 10. The processing apparatus according to claim 9, wherein the water vapor supply unit has a mechanism for bringing the raw material gas into contact with stored water.

14. 11. The processing apparatus of claim 10, wherein the water vapor supply is within the processing chamber.

15. 15. The processing apparatus according to claim 9, wherein the concentration of carbon dioxide contained in the processing gas is 5 vol % or more.

16. 15. The processing apparatus according to claim 9, wherein the light source is arranged so that the ultraviolet light is irradiated onto the processing gas present in an atmosphere in which the object to be processed is present.

17. The processing apparatus according to any one of claims 9 to 14, characterized in that the light source, the gas supply port, and the water vapor supply unit are arranged so as to spray the processing gas irradiated with the ultraviolet light onto the object to be processed.

18. A processing device according to any one of claims 9 to 14; the source gas supply source connected to the gas supply port; A processing system comprising:

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