Processing method, processor, and processing system

Abstract

To provide a processing method and a processor with higher processing efficiency.SOLUTION: In a processing method, raw material gas which contains carbon dioxide and has oxygen concentration of 1000 ppm or less is irradiated with ultraviolet light having an emission wavelength of 227 nm or less, and inside a processing chamber isolated from an atmosphere space, the raw material gas irradiated with the ultraviolet light is brought in contact with a subject to be processed to process the subject to be processed. A processor comprises: a light source which emits ultraviolet light having an emission wavelength of 227 nm or less; and a processing chamber which can be isolated from outside, and has a region for mounting the subject to be processed inside thereof, and a raw material gas supply port connected to a raw material gas supply source which supplies raw material gas which contains carbon dioxide and has oxygen concentration of 1000 ppm or less, where the processor irradiates the raw material gas with the ultraviolet light, and brings the raw material gas after irradiation in contact with the subject to be processed to process the subject to be processed.SELECTED DRAWING: Figure 1

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 method of the present invention uses carbon dioxide gas as a raw material gas and obtains atomic oxygen from the carbon dioxide gas. That is, the treatment method of the present invention includes irradiating a raw material gas containing carbon dioxide and having an oxygen concentration of 1000 ppm or less with ultraviolet light having an emission wavelength of 227 nm or less, In a processing chamber isolated from the atmosphere, the source gas irradiated with the ultraviolet light is brought into contact with an object to be processed to process the object.

[0008] 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.

[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 P) is generated. O( 3 P) is O( 1 Like D), it can be used for surface modification and cleaning of the workpiece. It is worth noting that in an oxygen gas atmosphere, O( 3P) combines with oxygen molecules in the atmosphere and is converted into ozone, but in an atmosphere where the oxygen gas concentration is 1000 ppm or less, O( 3 P) is difficult to combine with oxygen molecules in the atmosphere, so a large amount of atomic oxygen O( 3 P) can be maintained. As a result, a large amount of atomic oxygen O( 3 This is the greatest advantage of obtaining atomic oxygen from carbon dioxide gas rather than oxygen gas.

[0010] In the treatment method, the concentration of carbon dioxide contained in the raw material 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.

[0011] The processing method may further comprise reducing the amount of carbon monoxide in the source gas irradiated with the ultraviolet light.

[0012] In the treatment method, the raw material gas with a reduced amount of carbon monoxide may be irradiated with the ultraviolet light again, and the irradiated raw material gas may be brought into contact with the object again to treat the object. For example, as shown in second and fourth embodiments described later, the raw material gas with a reduced amount of carbon monoxide may be reused.

[0013] The processing method may utilize a circulation mechanism that circulates the source gas irradiated with ultraviolet light and passes it through the workpiece again, thereby passing the source gas irradiated with ultraviolet light through the region where the ultraviolet light is irradiated and contacting the workpiece again. The circulation mechanism may be, for example, a return flow path for the source gas downstream of the processing chamber to the upstream of the processing chamber, as shown in the second and fourth embodiments described below, or a circulating gas flow path within the processing chamber, as shown in the fifth embodiment described below. The circulation mechanism may repeatedly irradiate the source gas with ultraviolet light and repeatedly contact the source gas with the workpiece.

[0014] In the processing method, a light source that emits ultraviolet light and the object to be processed may be arranged so that the ultraviolet light is irradiated onto the surface of the object to be processed. For example, the arrangement of the light source and the object to be processed shown in the first and second embodiments described later may be adopted.

[0015] The processing method includes arranging a light source that emits ultraviolet light and the object to be processed at a position where the ultraviolet light is not irradiated onto a surface of the object to be processed, The source gas may be brought into contact with the workpiece after being irradiated with the ultraviolet light. For example, the arrangement of the light source and the workpiece as shown in the third and fourth embodiments described later may be adopted.

[0016] The present invention is a processing device for processing a workpiece, The processing device includes: a light source that emits ultraviolet light having an emission wavelength of 227 nm or less; a processing chamber that can be isolated from the outside and has an area inside for placing an object to be processed, the processing chamber further having a raw material gas supply port connected to a raw material gas supply source; the raw material gas supplied from the raw material gas supply source contains carbon dioxide and has an oxygen concentration of 1000 ppm or less; The processing device irradiates the source gas with the ultraviolet light and brings the irradiated source gas into contact with the object to be processed, thereby processing the object.

[0017] In the processing apparatus, the concentration of carbon dioxide contained in the raw material gas supply source may be 5 vol% or more. When the concentration of carbon dioxide is 5 vol% or more, the O( 3 P) production efficiency increases.

[0018] The processing device may include a carbon monoxide reduction unit that introduces the raw material gas after the ultraviolet light irradiation and reduces the amount of carbon monoxide in the raw material gas. The carbon monoxide reduction unit may adsorb carbon monoxide by an adsorption method, or convert carbon monoxide to carbon dioxide by an incineration method or a catalytic oxidation method.

[0019] The processing device may be provided with a return flow path for the raw material gas, which is used to irradiate the raw material gas discharged from the carbon monoxide reduction section with ultraviolet light again and bring the irradiated raw material gas into contact with the workpiece again.

[0020] In the processing device, the light source and the area where the workpiece is placed may be positioned so that the ultraviolet light is irradiated onto the surface of the workpiece. For example, the light source and the area where the workpiece is placed may be positioned as shown in the first and second embodiments described below. The light source and the area where the workpiece is placed may be positioned opposite each other.

[0021] the processing apparatus includes a gas flow path through which the source gas flows and an outlet of the gas flow path disposed opposite the object to be processed, inside the processing chamber; The gas flow path may be formed along a light emission region of the light source, and the light source and the gas flow path may be arranged so that the gas flow path overlaps the light emission region, for example, in the arrangement relationship between the light source and the workpiece as shown in the third and fourth embodiments described later.

[0022] The processing system of the present invention comprises the processing device described above and a raw material gas supply source that supplies a raw material gas containing carbon dioxide and having an oxygen gas concentration of 1000 ppm or less to the treatment device; Equipped with. [Effects of the Invention]

[0023] This makes it possible to provide a processing method, processing apparatus, and processing system with improved processing efficiency. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a diagram illustrating a processing apparatus according to a first embodiment. [Figure 2] 1 is a diagram showing a processing system including a processing apparatus according to a first embodiment; [Figure 3] FIG. 10 is a diagram showing a modified example of the processing apparatus of the first embodiment. [Figure 4] 1 is a graph showing experimental results of the O / C ratio. [Figure 5] 1 is a graph showing experimental results of water contact angle. [Figure 6A] 10 is a graph showing the results of a simulation in which the oxygen concentration is varied. [Figure 6B] 10 is a graph showing the results of a simulation in which the oxygen concentration is varied. [Figure 7A] 10 is a graph showing the simulation results of O(3P) concentration when carbon dioxide is not used. [Figure 7B] 10 is a graph showing simulation results of O(3P) concentration when carbon dioxide concentration is not used. [Figure 7C] 10 is a graph showing simulation results of O(3P) concentrations with different carbon dioxide concentrations. [Figure 8] FIG. 10 is a diagram illustrating a processing apparatus according to a second embodiment. [Figure 9] FIG. 10 is a diagram illustrating a processing apparatus according to a third embodiment. [Figure 10] FIG. 10 is a diagram illustrating a processing apparatus according to a fourth embodiment. [Figure 11] FIG. 10 is a diagram illustrating a processing apparatus according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0025] 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.

[0026] 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.

[0027] First Embodiment [Processing equipment overview] An embodiment of a processing method and processing apparatus will be described with reference to Figure 1. 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 can be isolated from the outside and has an area inside for placing a workpiece 10 to be processed. Inside the processing chamber 2, the ultraviolet light L1 emitted from the light source 1 is irradiated onto the workpiece 10. The type of light source used for the light source 1 is not particularly limited.

[0028] 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.

[0029] 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.

[0030] 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 is a placement location (not shown) for 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 placed from the space where the workpiece 10 is placed. 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). The space where the light source 1 is placed is filled with a gas that does not easily absorb ultraviolet light L1 (e.g., an inert gas such as nitrogen). Although not shown in FIG. 1 , a gas supply port for supplying gas and a gas exhaust port for exhausting gas from the space where the light source 1 is placed may be provided adjacent to the space where the light source 1 is placed. 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 where the light source 1 is placed also has the effect of cooling the light source 1. Note that the present invention may have a structure without the light-transmitting wall 4. The space in which the light source 1 is placed may be a vacuum (reduced pressure) environment.

[0031] The processing chamber 2 is provided with a raw material gas supply port 5 and a raw material gas exhaust port 6 adjacent to the space in which the workpiece 10 is placed. The raw material gas supply port 5 and the raw material gas exhaust port 6 are both holes provided in the housing 3. The raw material gas supply port 5 is connected to a raw material gas supply source (not shown). The raw material gas exhaust port 6 is connected to a gas suction source (not shown). The raw material gas supply port 5 and the raw material gas exhaust port 6 are arranged to sandwich the space above the workpiece 10, so that the raw material gas G1 supplied to the processing chamber 2 comes into contact with the surface of the workpiece 10 to be processed. The workpiece 10 may be processed while the raw material gas G1 is being supplied and exhausted, or the workpiece 10 may be processed while the supply and exhaust of the raw material gas G1 are stopped.

[0032] The processing apparatus 100 of this embodiment has a carbon monoxide reduction unit 9 between the raw material gas outlet 6 and the gas suction source. The carbon monoxide reduction unit 9 is an optional component in the processing apparatus 100, and the processing apparatus 100 does not necessarily have to be equipped with the carbon monoxide reduction unit 9. Details of the carbon monoxide reduction unit 9 will be described later.

[0033] The source gas G1 supplied to the processing chamber 2 contains carbon dioxide. The source gas G1 has an oxygen gas concentration of 1000 ppm or less. Ultraviolet light L1 in the above-mentioned wavelength range is irradiated onto the source gas G1 that contacts the workpiece 10. Carbon dioxide (hereinafter, sometimes referred to as "CO2") contained in the source 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.

[0034] The reason for using a gas containing carbon dioxide as the source gas G1 will be explained below by comparing the case where carbon dioxide is irradiated with ultraviolet light L1 with the case where oxygen gas is irradiated with ultraviolet light L1.

[0035] [When irradiating oxygen gas with ultraviolet light] When the wavelength λ of ultraviolet light L1 is greater than 175 nm and less than 242 nm, the photodecomposition of oxygen gas (O2) when the energy (hν) of ultraviolet light L1 is applied 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.

[0036] When the wavelength λ of ultraviolet light L1 is 175 nm or less, the photodecomposition of oxygen gas O2 when the energy (hν) of ultraviolet light L1 is given 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).

[0037] As shown in equations (1), (2), and (3), when ultraviolet light L1 is irradiated onto the workpiece 10 in contact with oxygen gas, O( 3 P) is generated. And the generated O( 3 P) often reacts with oxygen 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 O( 3P), and there was room for improvement in terms of efficiency.

[0038] [When carbon dioxide gas is irradiated with ultraviolet light] When the wavelength λ of ultraviolet light is greater than 166 nm and less than 227 nm, the photodecomposition of carbon dioxide gas (CO2) when ultraviolet light energy (hν) is applied to it is shown in equation (5). CO2+hν → CO+O( 3 P) (5) As shown in equation (5), photolysis produces ground-state atomic oxygen O( 3 P) and carbon monoxide are obtained.

[0039] When the wavelength λ of ultraviolet light is 166 nm or less, the photodecomposition of carbon dioxide gas (CO2) when ultraviolet light energy hν is applied to it is shown in equation (6). CO2+hν → CO+O( 1 D) (6) (6) 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).

[0040] As shown in equations (5), (6), and (3), UV light converts carbon dioxide gas into O( 3 P) is generated. However, the generated O( 3P) is hardly lost by reacting with carbon dioxide gas in the atmosphere or carbon monoxide produced by photolysis. This is different from an atmosphere containing oxygen gas. Therefore, the generated O( 3 P) can be efficiently used for surface modification and cleaning of the workpiece 10.

[0041] A secondary effect of irradiating ultraviolet light in a carbon dioxide atmosphere will be explained. Carbon dioxide gas is less absorbent than oxygen gas, so the workpiece 10 can be irradiated with ultraviolet light of high illuminance. For example, the absorption cross section of oxygen gas for vacuum ultraviolet light with a wavelength of 172 nm is approximately 6 × 10 -19 cm 2 whereas the absorption cross section of carbon dioxide gas is approximately 1×10 -20 cm 2 Because oxygen gas has a large absorption cross section, even in an air atmosphere containing only 21% oxygen gas, the reach of 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.

[0042] In the case of oxygen-independent phototreatment, carbon dioxide gas is used as O( 3 Since carbon dioxide is the only source of the fluorine-containing gas G1, carbon dioxide is essential. However, the main component of the source gas G1 does not necessarily have to be carbon dioxide. The main component of the source gas G1 may be an inert gas such as nitrogen. The inert gas enables photoprocessing when mixed with carbon dioxide. Nitrogen gas, in particular, has the same low attenuation of ultraviolet light as carbon dioxide, so it has the advantages of ensuring a long reach of vacuum ultraviolet light, being inexpensive, and being readily available.

[0043] [Carbon monoxide reduction section] When ultraviolet light L1 is irradiated onto a raw material gas containing carbon dioxide and having an oxygen concentration of 1000 ppm or less, carbon monoxide (CO) gas is generated, as shown in equations (5) and (6). The generated carbon monoxide gas is discharged from the raw material gas outlet 6. Because carbon monoxide gas is toxic, it is desirable to reduce the carbon monoxide. Therefore, a carbon monoxide reduction unit 9 may be disposed downstream of the raw material 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 contains an adsorbent that adsorbs carbon monoxide. The adsorbent 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, may be introduced into the carbon monoxide reduction unit 9 and brought into contact with the carbon monoxide gas. In addition, various means for reacting with carbon monoxide to convert it to carbon dioxide may be adopted and applied as the carbon monoxide reduction unit 9. Note that, since the reduction of carbon monoxide is not directly related to the modification or cleaning of the workpiece, the carbon monoxide reduction unit 9 is not an essential component of the processing apparatus 100 of this embodiment.

[0044] [Processing system overview] 2 shows a processing system 150. The processing system 150 includes a processing device 100 and a source gas supply source that supplies source gas to the processing device 100. The processing system 150 of this embodiment has a nitrogen (N2) gas supply source 110 and a carbon dioxide (CO2) gas supply source 120 as source gas supply sources. A gas mixing valve 130 is provided between the processing device 100 and the nitrogen gas supply source 110 and the carbon dioxide gas supply source 120. The gas mixing valve can automatically or manually adjust the ratio between the amount of nitrogen gas supplied from the nitrogen gas supply source 110 and the amount of carbon dioxide supplied from the carbon dioxide gas supply source 120.

[0045] [experiment] An experiment was conducted to verify the effect of irradiating ultraviolet light in a carbon dioxide atmosphere. A processing device 200 shown in FIG. 3 was used for the verification experiment. The processing device 200 is a modified version of the processing device 100. The processing device 200 differs from the processing device 100 shown in FIG. 1 in that the light source 1 and the workpiece 10 are not separated by a light-transmitting wall 4, but are instead arranged in close proximity to each other. In the processing device 200, the distance d1 between the light source 1 and the workpiece 10 is set to 1 mm. The light source 1 is a xenon excimer lamp (main emission wavelength 172 nm, illuminance at d1=0 30 mW / cm 2 ) was used.

[0046] Four samples were prepared for the experiment. All four samples were made of polypropylene resin (PP). The experiment was carried out by connecting a CDA gas supply source (not shown) or a carbon dioxide gas supply source (not shown) to the raw material gas supply port 5 of the processing device 100. The light irradiation conditions for each sample were as follows:

[0047] [Table 1]

[0048] "CDA" in Table 1 stands for Clean Dry Air, i.e., a mixed gas consisting of approximately 78% nitrogen gas, approximately 21% oxygen gas, and less than 1% other gases, including carbon dioxide. "CO2" in Table 1 stands for nearly 100% carbon dioxide gas. By irradiating the sample PP with ultraviolet light L1 for the time listed in Table 1, hydrophilic functional groups such as OH groups, C=O groups, or COOH groups are added to the surface of the PP, thereby modifying the surface to make it hydrophilic.

[0049] Figures 4 and 5 show the experimental results. Figure 4 shows the O / C ratio (the ratio of oxygen atoms to carbon atoms) on the surface of each of the treated samples S1–S4. The O / C ratio was calculated by measuring the surface of each treated sample S1–S4 using an XPS (PHI Quantera SXM, manufactured by ULVAC-PHI, Inc.). Specifically, the photoelectron intensity from oxygen atoms emitted from the sample surface and the photoelectron intensity from carbon atoms were used to calculate the concentration of each atom. The O / C ratio was then calculated by dividing the oxygen atom concentration by the carbon atom concentration. Since the untreated sample (PP) surface has no oxygen atoms, the O / C ratio is nearly zero. However, as hydrophilization progresses and the number of oxygen atoms on the surface increases, the O / C ratio increases. Therefore, the higher the O / C ratio, the more the sample's surface has been modified (hydrophilized).

[0050] Figure 4 shows that the surface modification of samples S3 and S4, which were irradiated with light in a carbon dioxide atmosphere, was more advanced than that of samples S1 and S2, which were irradiated with light in a CDA atmosphere. Since sample S3 was irradiated with light for the same time as sample S1, and sample S4 was irradiated with light for the same time as sample S2, it can be seen that the treatment efficiency is higher when the sample is irradiated with light in a carbon dioxide atmosphere than when the sample is irradiated with light in a CDA atmosphere. Furthermore, a comparison of samples S3 and S4 shows that the longer the treatment time, the more the phototreatment progresses.

[0051] FIG. 5 shows the measurement results of the water contact angle of each sample (S1 to S4) treated under the conditions in Table 1. A contact angle meter DMs-401 manufactured by Kyowa Interface Science Co., Ltd. was used to measure the water contact angle. 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, "Test method for wettability of substrate glass surfaces." The measurement results are shown in FIG. 5.

[0052] In Figure 5, S0, with an irradiation time of 0 seconds, represents the water contact angle (103°) of the untreated sample (PP). A smaller water contact angle indicates greater hydrophilicity. Experimental results confirmed that each sample became more hydrophilic, regardless of whether the irradiation time was 30 seconds or 120 seconds. However, samples S3 and S4, which were irradiated under a carbon dioxide atmosphere, showed greater hydrophilicity than samples S1 and S2, which were irradiated under a CDA atmosphere. Furthermore, since sample S3 was irradiated for the same amount of time as sample S1, and sample S4 was irradiated for the same amount of time as sample S2, it was also found that phototreatment under a carbon dioxide atmosphere resulted in greater hydrophilicity than phototreatment under a CDA atmosphere.

[0053] [Oxygen concentration simulation] By performing the simulation, the oxygen concentration in the irradiation atmosphere was varied, and the O( 3 Figure 6A shows the results of an oxygen concentration simulation in an atmosphere dominated by carbon dioxide except for a small amount of oxygen. The results show the O( 3 P) Concentration (1cm 3 Hit O( 3 The "Reference" shown to the right of each oxygen gas concentration is the result of O( 3 P) 3 Specifically, the O( 3 The maximum O( 3 P) The E+N in the concentration value represents 10 to the Nth power. For example, 1.00E+12 is 1.00 x 10 12 Represents.

[0054] The simulation conditions are as follows: The processing apparatus is assumed to be the processing apparatus 200 shown in FIG. 3. 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=1cm. The pressure is 1 atmosphere and the temperature is 300K (27℃). O( 3 The O( P) concentration was calculated as follows. First, the attenuation of ultraviolet light by oxygen gas and carbon dioxide gas was calculated using known absorption coefficients, and the illuminance (amount of energy) on the surface of the workpiece 10 was calculated for each oxygen concentration. Next, the O( P) concentration was calculated based on the illuminance on the surface of the workpiece 10, the initial concentrations of possible chemical species, and the known reaction rate constants of chemical reactions related to each chemical species. 3 P) concentration was calculated.

[0055] The higher the oxygen gas concentration, the more difficult it is for light to reach the O( 3 Therefore, it was expected that the lower the oxygen concentration, the higher the treatment efficiency. However, according to the simulation results, as shown in Figure 6A, when the oxygen gas concentration is 10 ppm or less, almost no O( 3 Furthermore, from Figure 6A, it can be seen that the O( 3 P) concentration is 10000 ppm O( 3 Furthermore, if the oxygen gas concentration is 1000 ppm or less, the O( 3 P) than to generate a higher O( 3 This is because the addition of carbon dioxide results in an amount of O( 3 This indicates that an oxygen gas concentration of 1000 ppm or less can be achieved in the ultraviolet light irradiation atmosphere. It has been found that the oxygen gas concentration in the ultraviolet light irradiation atmosphere is preferably 100 ppm or less, and more preferably 10 ppm or less.

[0056] Figure 6B shows the results of an oxygen concentration simulation in an atmosphere where carbon dioxide and nitrogen are mixed in a ratio of 1:9, except for a small amount of oxygen. The results show the O( 3 The "Reference" shown to the right of each oxygen gas concentration is the result of using only oxygen gas without carbon dioxide and O( 3 P) 3 P) concentration. In Figure 6B, the O( 3 P) concentration is 10000 ppm O( 3 Furthermore, if the oxygen gas concentration is 1000 ppm or less, the O( 3 P) than to generate a higher O( 3 This is because the addition of carbon dioxide results in an amount of O( 3 This indicates that an oxygen gas concentration of 1000 ppm or less can be achieved in the ultraviolet light irradiation atmosphere. It has been found that the oxygen gas concentration in the ultraviolet light irradiation atmosphere is preferably 100 ppm or less, and more preferably 10 ppm or less.

[0057] 6A and 6B were simulations based on the assumption that the light source 1 was located at a distance of d1 = 1 cm from the surface of the workpiece 10, but it was found that the same trends as those in Fig. 6A and 6B were observed even when d1 was changed. It is also estimated that the same trends would be observed even if the wavelength or illuminance of the light source 1 was changed.

[0058] [Carbon dioxide concentration simulation] The preferred concentration of carbon dioxide gas in the irradiation atmosphere was investigated. First, we investigated the O( 3 Figure 7A shows the amount of 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.

[0059] 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. 3. 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).

[0060] As shown in FIG. 7A, 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).

[0061] As in Figure 7A, Figure 7B shows the O( 3 7A, it is assumed that the light source 1 is located at a distance of d1 = 0.1 cm from the surface of the workpiece 10. The other simulation conditions are the same as those in FIG. 7A.

[0062] As shown in FIG. 7B, 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.

[0063] 7A and 7B 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 / cm 3 , which exceeds O( 3 It is preferred to produce P).

[0064] Figure 7C shows the results of a dioxygen concentration simulation under light irradiation in an atmosphere composed of carbon dioxide, nitrogen, and oxygen gases. The carbon dioxide concentration represents the proportion of carbon dioxide gas in a mixed gas composed of carbon dioxide and nitrogen gases. All carbon dioxide concentrations were calculated under the condition that 1000 ppm of oxygen gas was separately added. Strictly speaking, the carbon dioxide concentration is defined as the proportion of carbon dioxide gas in a mixed gas composed of carbon dioxide, nitrogen, and oxygen gases. However, since the proportion of oxygen gas in a mixed gas of 1000 ppm is a very small amount, far less than 1%, in practice, the proportion of carbon dioxide gas in a gas composed of carbon dioxide and nitrogen gas can be referred to as the carbon dioxide concentration without considering the small amount of oxygen gas.

[0065] The O( 3 P) Concentration (1cm 3 Hit O( 3 This is the result of calculating the number of O( 3 The notation of P) concentration is as described above. 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 processing device is assumed to be the processing device 200 shown in Figure 3. 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).

[0066] As can be seen in Figure 7C, unlike the tendency of oxygen concentration when only oxygen gas is used, the amount of O( 3 P) concentration increases. And when the carbon dioxide concentration is 2 vol%, O( 3 P) concentration is 2.4 × 10 12 pieces / cm 3 The maximum O( 3 P) Concentration (2.5×10 12 pieces / cm 3 However, when the carbon dioxide concentration exceeds 5 vol%, O( 3 P) concentration is 3.0 × 10 12 pieces / cm 3 The maximum O( 3 In other words, by using carbon dioxide gas of 5 vol% or more, the O( 3 P) concentration can be produced.

[0067] In the above simulation, the distance d1 from the light source to the surface of the workpiece 10 is set to 1 cm. However, even if the distance d1 from the light source to the surface of the workpiece 10 is 0.1 cm, when the carbon dioxide concentration exceeds 5 vol%, the maximum O( 3 In addition, the above simulation was performed under the condition that the oxygen concentration was set to 1000 ppm, but even if the oxygen concentration is lower than 1000 ppm, the higher the carbon dioxide concentration, the higher the O( 3 P) concentration increases, the situation remains unchanged.

[0068] Second Embodiment The second embodiment will be described with reference to FIG. 8. 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.

[0069] The processing apparatus 300 shown in FIG. 8 has a return flow path 31 that returns the gas discharged from the processing chamber 2 to the upstream side of the processing chamber 2. The return flow path 31 is connected to the main flow path by flow path switching valves (32, 33). Although not shown in FIG. 8, the return flow path 31 may be provided with a pump for circulating the gas. In the carbon monoxide reduction unit 9, the amount of raw material gas required can be reduced by converting carbon monoxide to carbon dioxide using incineration or contact oxidation.

[0070] In one pass through the processing chamber 2, all of the carbon dioxide gas contained in the source gas supplied to the processing chamber 2 is converted into O( 3 P), and the raw material gas discharged from the processing chamber 2 still contains a large amount of carbon dioxide gas. Therefore, the raw material 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 raw material gas is reused. This allows for efficient use of carbon dioxide and reduces costs. The raw material gas containing carbon dioxide passes through the processing chamber 2 a predetermined number of times and is decomposed into O( 3The flow path switching valves (31, 32) may be controlled so that the raw material gas (P) is repeatedly generated and then discharged. 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 the unused source gas to the used source gas can be controlled.

[0071] Third Embodiment A processing apparatus according to a fourth embodiment will be shown with reference to FIG. 9. This processing apparatus is a type of processing apparatus that sprays a raw material gas irradiated with light toward the surface of a workpiece 10. The processing apparatus 400 is provided with a gas flow path 8 inside a processing chamber 2 through which a raw material 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. As a result, atomic oxygen O( 3 The raw material 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.

[0072] The workpiece 10 may be placed on a movable stage and processed by scanning the workpiece 10 under the outlet 45 from which the source 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 first and second embodiments described above, and the fourth and fifth embodiments described below.

[0073] <Fourth embodiment> Referring to Figure 10, a processing apparatus according to a fourth embodiment is shown. Figure 10 shows the apparatus shown in the third embodiment, which allows the raw material gas to be reused. The raw material gas discharged from the processing chamber 2 is returned upstream of the processing chamber 2 using a return flow path 31, allowing the raw material gas to be reused. This allows for efficient use of carbon dioxide, leading to cost reductions. By using an incineration method or a contact oxidation method in the carbon monoxide reduction unit 9 to convert carbon monoxide to carbon dioxide, the amount of raw material gas required can be reduced.

[0074] Fifth Embodiment A processing apparatus according to a fifth embodiment is shown in FIG. 11 . Unlike the processing apparatus 400 according to the fourth embodiment, the processing apparatus 500 according to the fifth embodiment circulates and reuses the source gas within the processing chamber 2. The processing apparatus 500 includes a suction port 51 upstream of the light source 1 for sucking in gas within the processing chamber 2, and a suction fan 52. The processing apparatus 500 then sucks in the source gas G1 irradiated with ultraviolet light, irradiates the sucked source gas G1 with ultraviolet light again, and brings the irradiated source gas G1 back into contact with the workpiece 10. A carbon monoxide-reducing catalyst may also be disposed within the processing chamber 2 as a carbon monoxide reduction unit. In a processing chamber 2 equipped with such a catalyst, the amount of source gas required can be reduced by converting carbon monoxide to carbon dioxide during the process of circulating and reusing the source gas.

[0075] While the raw material gas G1 is circulated within the processing chamber 2 for a predetermined time, the supply of the raw material gas G1 from the raw material gas supply port 5 and the discharge of the raw material gas G1 from the raw material gas discharge port 6 may be stopped or continued.

[0076] 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 without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0077] 1:Light source 2: Processing chamber 3: Housing 4: Translucent wall 5: Raw material gas supply port 6: Raw material gas outlet 8: Gas flow path 9: Carbon monoxide reduction unit 10: Work (processing object) 31: Return flow path 45: Outlet 51: Suction port 52: Suction fan 100, 200, 300, 400, 500: Processing equipment 110: Nitrogen gas supply source 120: Carbon dioxide gas source 130: Gas mixing valve 150: Processing System G1: Raw material gas L1: Ultraviolet light

Claims

1. A raw material gas containing carbon dioxide and having an oxygen concentration of 1000 ppm or less is irradiated with ultraviolet light having an emission wavelength of 227 nm or less, A processing method comprising the steps of: bringing the source gas irradiated with the ultraviolet light into contact with an object to be processed in a processing chamber isolated from atmospheric space.

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

3. 2. The processing method according to claim 1, wherein the amount of carbon monoxide in the source gas irradiated with the ultraviolet light is reduced.

4. 4. The processing method according to claim 3, wherein the raw material gas in which the amount of carbon monoxide has been reduced is irradiated with the ultraviolet light again, and the irradiated raw material gas is brought into contact with the object to be processed again, thereby processing the object to be processed.

5. 2. The processing method according to claim 1, characterized in that a circulation mechanism is used to circulate the raw material gas irradiated with the ultraviolet light and pass it through the object to be processed again, thereby passing the raw material gas irradiated with the ultraviolet light through a region where the ultraviolet light is irradiated again and bringing the raw material gas into contact with the object to be processed again.

6. The processing method according to any one of claims 1 to 5, wherein a light source that emits the ultraviolet light and the object to be processed are arranged so that the ultraviolet light is irradiated onto the surface of the object to be processed.

7. a light source that emits the ultraviolet light and the object to be treated are placed at a position where the ultraviolet light is not irradiated onto the surface of the object to be treated, 6. The processing method according to claim 1, wherein the source gas is brought into contact with the object to be processed after being irradiated with the ultraviolet light.

8. A processing apparatus for processing a workpiece, The processing device includes: a light source that emits ultraviolet light having an emission wavelength of 227 nm or less; a processing chamber that can be isolated from the outside and has an area inside for placing an object to be processed, the processing chamber further having a raw material gas supply port connected to a raw material gas supply source; the raw material gas supplied from the raw material gas supply source contains carbon dioxide and has an oxygen concentration of 1000 ppm or less; The processing apparatus is characterized in that the processing apparatus irradiates the source gas with the ultraviolet light and brings the irradiated source gas into contact with the object to be processed, thereby processing the object.

9. 9. The processing apparatus according to claim 8, wherein the concentration of carbon dioxide contained in said raw material gas supply source is 5 vol % or more.

10. 9. The processing apparatus according to claim 8, further comprising a carbon monoxide reducing unit that reduces the amount of carbon monoxide in the source gas after the irradiation with the ultraviolet light.

11. 11. The processing apparatus according to claim 10, further comprising a return flow path for the raw material gas, which is configured to irradiate the raw material gas discharged from the carbon monoxide reduction section with the ultraviolet light again and bring the irradiated raw material gas into contact with the object to be processed again.

12. 10. The processing apparatus according to claim 9, wherein the light source and the area where the object to be processed is placed are positioned so that the ultraviolet light is irradiated onto the surface of the object to be processed.

13. a gas flow path through which the source gas flows and an outlet of the gas flow path that is disposed opposite the object to be processed, the gas flow path being provided inside the processing chamber; 10. The processing apparatus according to claim 9, wherein the gas flow path is formed along a light emission region of the light source, and the light source and the gas flow path are arranged so that the gas flow path overlaps the light emission region.

14. The processing device according to any one of claims 8 to 13; a raw material gas supply source that supplies a raw material gas containing carbon dioxide and having an oxygen concentration of 1000 ppm or less to the treatment device; A processing system comprising:

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