Gas concentration measuring device and gas concentration measuring method

Abstract

Provided are a gas concentration measuring device and a gas concentration measuring method which are capable of achieving both high sensitivity and noise immunity during measurement when ultraviolet light having a wavelength of 115-320 nm is used as a light source for measurement. A gas concentration measurer (100) is provided with: a chamber (1) through which a gas to be measured, which contains a component to be measured and a carrier gas, flows; a light source (2) that irradiates ultraviolet light having a wavelength of 115-320 nm (inclusive) to the gas to be measured that flows through the chamber (1); a light receiver (3) that receives transmitted light of the ultraviolet light that has passed through the gas to be measured; and an optical filter (6) that is provided on an optical path (L) of the ultraviolet light between the light source (2) and the light receiver (3), and that transmits only a specific wavelength band in the ultraviolet light.

Description

Technical Field

[0001] This invention relates to a gas concentration measuring instrument and a gas concentration measuring method. Background Technology

[0002] In semiconductor manufacturing processes, precise concentration management of various raw material gases supplied to the manufacturing equipment is crucial. For example, semiconductor manufacturing materials such as diborane require particularly high-precision concentration management. However, highly reactive gases like diborane are prone to chemical changes such as decomposition, both during storage in tanks or cylinders and during the supply process, making concentration management during semiconductor manufacturing difficult. Therefore, there is a need for concentration management through in-line or on-line gas concentration measurement during the semiconductor manufacturing supply process. Methods for gas concentration measurement, such as those using ultrasound, infrared light, and vacuum ultraviolet light, are known.

[0003] Japanese Patent Publication No. 2014-74629 (Patent Document 1) discloses a gas sensor. This gas sensor includes a tube for introducing gas, a light source for illuminating the tube, a first detection element, a second detection element, and a temperature measuring element for measuring the ambient temperature. It also includes an arithmetic unit for performing calculations using the output values ​​of the first and second detection elements, the measured value from the temperature measuring element, etc. The light source is an infrared light source that irradiates infrared light.

[0004] Japanese Patent Publication No. 2016-183972 (Patent Document 2) discloses a vacuum ultraviolet absorption spectroscopy system. This spectroscopy system includes a vacuum ultraviolet light source module, a flow cell, and a detector module. The light beam passing through the flow cell is focused onto the incident aperture of a beam splitter. The light passing through the aperture is collected by a grating, diffracted, and focused onto the detector for recording by a computer. In this spectroscopy system, the environment within the source module is maintained such that the concentration of the absorbing components of vacuum ultraviolet light (oxygen, water, etc.) is sufficiently low that the absorbing components do not absorb much of the photon flux of the vacuum ultraviolet light. This can be achieved through vacuum purging or purging with a gas that does not absorb vacuum ultraviolet light, such as nitrogen, helium, or hydrogen.

[0005] (Existing technical documents)

[0006] (Patent Documents)

[0007] Patent Document 1: Japanese Patent Application Publication No. 2014-74629

[0008] Patent Document 2: Japanese Patent Application Publication No. 2016-183972 Summary of the Invention

[0009] (The problem that the invention aims to solve)

[0010] In the measurement of gas concentration using ultrasonic methods or infrared light, sufficient sensitivity and noise immunity (high signal-to-noise ratio (SN ratio)) cannot be obtained, which cannot meet the needs of higher precision gas concentration management in semiconductor manufacturing processes.

[0011] Short-wavelength ultraviolet light, such as vacuum ultraviolet light and deep ultraviolet light, specifically ultraviolet light with wavelengths above 115 nm and below 320 nm (hereinafter, for convenience, sometimes referred to as specific wavelength ultraviolet light), is strongly absorbed by many substances, making it suitable for use as measurement light. However, precisely because of this strong absorption by many substances, specific wavelength ultraviolet light is easily affected by absorbing gases such as oxygen in the atmosphere when used for measurement. Therefore, when using specific wavelength ultraviolet light as a measurement light source, it may be difficult to obtain sufficient sensitivity and noise immunity (high signal-to-noise ratio) during the measurement process.

[0012] For example, in a gas concentration measuring device utilizing vacuum ultraviolet light, such as the vacuum ultraviolet absorption spectroscopy system disclosed in Patent Document 2, operations such as evacuating the light source module or replacing it with a gas that does not absorb vacuum ultraviolet light are performed to suppress the absorption of vacuum ultraviolet light within the light source module. In gas concentration measuring devices using ultraviolet light of a specific wavelength, such as vacuum ultraviolet light, especially when a spectrometer is used, the same operations are performed within the spectrometer as in the case of the light source module; otherwise, absorption of the specific wavelength of ultraviolet light will occur within the spectrometer, and insufficient sensitivity may not be obtained during measurement. However, if the structure of the spectrometer is restricted to suit the operation of the atmosphere (ambient gas) within the spectrometer, sufficient sensitivity may still not be obtained when measuring with specific wavelength ultraviolet light. Therefore, it is necessary to improve the sensitivity of gas concentration measuring devices and gas concentration measurement methods that use specific wavelength ultraviolet light as a light source for gas concentration measurement.

[0013] This disclosure is made in view of the above-mentioned actual situation, and its purpose is to provide a gas concentration measuring instrument and gas concentration measuring method that can take into account both high sensitivity and noise immunity when using ultraviolet light with a wavelength of 115 nm or higher and 320 nm or lower as the light source for measurement.

[0014] (The measures taken to solve the problem)

[0015] To achieve the above objectives, the gas concentration measuring device disclosed herein comprises:

[0016] A chamber through which the gas containing the measured component and the carrier gas flows;

[0017] A light source that irradiates the gas to be measured in the chamber with ultraviolet light having a wavelength between 115 nm and 320 nm.

[0018] A light receiver that receives transmitted light through the ultraviolet light emitted by the gas being measured; and

[0019] An optical filter is disposed in the optical path of the ultraviolet light between the light source and the light receiver.

[0020] The optical filter allows only specific wavelengths of the ultraviolet light to pass through.

[0021] The gas concentration measurement method disclosed herein, in order to achieve the above objectives, includes:

[0022] The flow process involves passing a carrier gas that does not have an absorption wavelength in the ultraviolet light band with wavelengths above 115 nm and below 320 nm, and a measurement target gas formed by mixing the measurement target component that has an absorption wavelength in the ultraviolet light band, through a chamber.

[0023] An irradiation process, wherein the gas to be measured is irradiated with ultraviolet light flowing through the chamber; and

[0024] The light-receiving process involves receiving transmitted light from the ultraviolet light that has passed through the gas being measured.

[0025] The irradiation process or the light-receiving process includes a filtering process that selects a specific wavelength band.

[0026] (The effect of the invention)

[0027] According to this disclosure, a gas concentration measuring instrument and a gas concentration measuring method can be provided that can balance high sensitivity and noise immunity during measurement when using ultraviolet light with a wavelength of 115 nm or more and 320 nm or less as the light source for measurement. Attached Figure Description

[0028] Figure 1 This is a diagram illustrating the structure of the gas concentration measuring device involved in this embodiment.

[0029] Figure 2 A graph showing the results of Examples 1 to 5.

[0030] Figure 3 A graph showing the results of Examples 6 to 8.

[0031] Figure 4 A graph showing the results of Comparative Examples 1 to 4.

[0032] Figure 5 A graph showing the results of Comparative Example 5.

[0033] Figure 6 This is a diagram used to illustrate the structure of other gas concentration measuring devices. Detailed Implementation

[0034] Referring to the accompanying drawings, the gas concentration measuring device and gas concentration measuring method involved in the embodiments of this disclosure will be described.

[0035] Figure 1 A diagram illustrating the structure of the gas concentration measuring device 100 according to this embodiment is shown. The gas concentration measuring device 100 includes: a cell 1 through which a target gas containing a target component and a carrier gas flows; a light source unit 2 that irradiates the target gas flowing through the cell 1 with ultraviolet light having a wavelength of 115 nm or more and 320 nm or less; a light receiver 3 that receives transmitted light from the ultraviolet light passing through the target gas; and a filter window 6, which is an optical filter disposed on the optical path L of the ultraviolet light between the light source unit 2 and the light receiver 3, the filter 6 allowing only specific wavelengths of the ultraviolet light to pass through.

[0036] The gas concentration measurement method according to this embodiment includes: a flow step in which a carrier gas having no absorption wavelength in the ultraviolet light band with a wavelength of 115 nm or more and 320 nm or less is mixed with a measurement target component having an absorption wavelength in the ultraviolet light band, and the mixture is flowed into a chamber 1; an irradiation step in which the measurement target gas flowing into the chamber 1 is irradiated with ultraviolet light of the band; and a light receiving step in which the transmitted light of the ultraviolet light passing through the measurement target gas is received, wherein the irradiation step or the light receiving step includes a filtering step for selecting a specific band.

[0037] The gas concentration measuring device 100 can realize the gas concentration measurement method described above. According to the gas concentration measuring device 100 and the gas concentration measurement method, when ultraviolet light is used as the light source for measurement, the sensitivity and noise immunity during measurement can be improved, while maintaining both high sensitivity and noise immunity during measurement.

[0038] The following is a detailed description of the gas concentration measuring instrument 100 and the gas concentration measurement method.

[0039] As described above, the gas concentration measuring device 100 includes a chamber 1, a light source unit 2, a light receiver 3, and a filter window 6. As an example, the gas concentration measuring device 100 may also include: a first container 51 that surrounds the space containing the light path L of ultraviolet light between the light source unit 2 and the chamber 1; a second container 52 that surrounds the space containing the light path L of transmitted light between the chamber 1 and the light receiver 3; and a condenser lens 7 disposed on the light path L of ultraviolet light between the light source unit 2 and the chamber 1. In the gas concentration measuring device 100, the concentration of the target component in the target gas is measured based on the absorption of ultraviolet light by the target component in the target gas containing the target component and the carrier gas. Hereinafter, the wavelength range of 115 nm and above to 320 nm may be referred to as a specific wavelength band.

[0040] The carrier gas is a gas used to mix in the component to be measured. In the gas concentration measuring instrument 100, the concentration of the component to be measured in the gas is measured under the premise that the carrier gas does not have an absorption wavelength that overlaps with the component to be measured in a specific band.

[0041] The carrier gas is preferably a gas that does not have an absorption wavelength in a specific wavelength range, particularly in the range of wavelengths above 130 nm and below 320 nm. Furthermore, the carrier gas is preferably a gas that is inexpensive to obtain. Examples of such carrier gases include N2 (nitrogen), H2 (hydrogen), and CO2 (carbon dioxide).

[0042] The measured component can be any gaseous substance that has an absorption wavelength within a specific wavelength range. Examples of gaseous components that have absorption wavelengths within a specific wavelength range and require high-precision concentration management in semiconductor manufacturing processes include B₂H₆ (diborane), N₂H₄ (hydrazine), Si₂H₆ (disilane), Ge₂H₆ (digermane), and MoO₂Cl₂ (vaporized molybdenum dichlorodioxide). These gases are used as feedstock gases in semiconductor manufacturing processes. B₂H₆, N₂H₄, Si₂H₆, Ge₂H₆, and MoO₂Cl₂ exhibit significant absorption in specific wavelength ranges, specifically approximately 115 nm to 140 nm, 130 nm to 195 nm, 125 nm to 170 nm, 120 nm to 185 nm, and 245 nm to 315 nm.

[0043] The components being measured are not limited to the gas used as a raw material; they can also be impurities. For example, one could cite cases where IPA (isopropanol) is mixed into carbon dioxide used as a carrier gas as an impurity gas.

[0044] Chamber 1 is a container for the flow of the gas to be measured and for the transmission of ultraviolet light of a specific wavelength through the gas. Ultraviolet light of a specific wavelength, irradiated by the light source unit 2, is introduced into chamber 1 and passed through the gas to be measured. The transmitted ultraviolet light of the specific wavelength that has passed through the gas is then directed out of chamber 1 for reception by the light receiver 3. The light source unit 2 and the light receiver 3 will be described in detail later.

[0045] The chamber 1 includes: a cylindrical portion 10 having a linear internal space; an incident portion 11 disposed at one end of the cylindrical portion 10; an exit portion 12 disposed at the end of the cylindrical portion 10 opposite to the incident portion 11; an inlet 15 supplying the gas to be measured to the cylindrical portion 10; and an outlet 16 discharging the gas to be measured from the cylindrical portion 10. In the chamber 1, the incident portion 11 is disposed on the side of the light source unit 2, and the exit portion 12 is disposed on the side of the light receiver 3.

[0046] In chamber 1, the gas to be measured flows through the cylinder 10 while ultraviolet light of a specific wavelength passes through it. The gas to be measured is supplied to the cylinder 10 through inlet 15. The gas to be measured supplied to the cylinder 10 is discharged from outlet 16.

[0047] For example, when the gas being measured is a manufacturing gas including a raw material gas supplied to a semiconductor manufacturing apparatus, the inlet 15 is connected upstream of the supply pipe for the manufacturing gas, and the outlet 16 is connected downstream of the supply pipe for the manufacturing gas. In this case, the inlet 15, the cylinder 10, and the outlet 16 can be part of the supply pipe for the manufacturing gas or a bypass pipe of the supply pipe for the manufacturing gas. That is, the gas concentration measuring instrument 100 can be used for both in-line and on-line measurements.

[0048] The inlet 15 and outlet 16 are respectively positioned towards one end and the other end of the cylinder 10. This facilitates a uniform flow of the gas being measured along the axial direction of the cylinder 10 within the cylinder 10. Figure 1 The diagram shows a configuration where an inlet 15 is located at the end of the cylinder 10 near the side where the injection portion 11 is located, and an outlet 16 is located at the end of the cylinder 10 near the side where the exit portion 12 is located. Alternatively, the arrangement of the inlet 15 and outlet 16 can also be... Figure 1 The example shown is the opposite.

[0049] The incident section 11 is the light inlet that guides ultraviolet light of a specific wavelength from the light source unit 2 into the cavity 1 (the internal space of the cavity 1). The incident section 11 has a window 41 that allows all wavelengths of the ultraviolet light of the specific wavelength to pass through, or selects only a specific wavelength of the ultraviolet light of the specific wavelength to pass through and guide it into the cavity 1. As an example, the window 41 can be a flat plate shape such as a disc. In addition, selecting only a specific wavelength to pass through can also be described as blocking light of wavelengths other than the specific wavelength.

[0050] The incident portion 11 can, for example, be formed as a flange that clamps and fixes the window portion 41. As an example, in... Figure 1 The image shows an incident portion 11 having an annular and plate-shaped base 11a whose inner periphery is fixed to the end of the cylindrical portion 10, and an annular and plate-shaped cover portion 11b fixed to the base 11a by means of, for example, bolts and nuts. The window portion 41 is clamped by the base 11a and the cover portion 11b and thus fixed to the incident portion 11.

[0051] The emission section 12 is a light outlet that guides transmitted light from inside the chamber 1 to the outside of the chamber 1. The emission section 12 has a window 42, which allows all wavelengths of ultraviolet light of a specific wavelength band to pass through or selects only a specific wavelength band of ultraviolet light of a specific wavelength band to pass through and guide it to the outside of the chamber 1. Like the window 41, the window 42 can be flat.

[0052] Like the incident portion 11, the exit portion 12 can be formed in the shape of a flange that clamps and fixes the window portion 42. As an example, in... Figure 1 The diagram shows that the emission section 12 has an annular and plate-shaped base 12a whose inner periphery is fixed to the end of the cylindrical section 10, and an annular and plate-shaped cover 12b that is fixed to the base 12a by means of, for example, bolts and nuts. The window section 42 is clamped by the base 12a and the cover 12b and thus fixed to the emission section 12.

[0053] When the window portions 41 and 42 are flat, the window portions 41 and 42 can be configured such that their plate surfaces are orthogonal to the axial direction of the cylindrical portion 10.

[0054] At least one of window portion 41 and window portion 42 may be a filter window 6, which has a substrate (window) formed of a material capable of transmitting ultraviolet light of a specific wavelength and an optical filter disposed on the substrate. The optical filter may be a bandpass filter that allows transmission only to a further specific wavelength within a specific wavelength range. In this embodiment, the specific wavelength range allowed to be transmitted by the optical filter (filter window 6) includes at least the absorption wavelength of the component being measured.

[0055] The optical filter (filter window 6) allows a bandwidth of 5 nm or more and 50 nm or less for the transmitted wavelength range, preferably 10 nm or more and 40 nm or less. This allows the gas concentration measuring device 100 to achieve both high sensitivity and high noise immunity. Furthermore, in this embodiment, bandwidth refers to the wavelength width between the long-wavelength side and the short-wavelength side corresponding to 50% of the maximum transmittance of the wavelength range allowed by the optical filter (filter window 6). Additionally, in this embodiment, the wavelength range allowed by the optical filter (hereinafter, sometimes simply referred to as the transmission band) refers to the band above the wavelength of the long-wavelength side and below the wavelength of the short-wavelength side corresponding to 50% of the maximum transmittance of the wavelength range allowed by the optical filter. Both window 41 and window 42 can be filter windows 6, or only one of them can be a filter window 6. In the gas concentration measuring device 100, the noise of light received by the photodetector 3 (described later) can be reduced (improving the signal-to-noise ratio) through the filter window 6.

[0056] The other of window 41 and window 42 can be a window made of a material that allows ultraviolet light of a specific wavelength to pass through.

[0057] As an example, a substrate made of a material that allows ultraviolet light of a specific wavelength to pass through, or a window made of a material that allows ultraviolet light of a specific wavelength to pass through, can be formed from MgF2 (magnesium fluoride). MgF2 has high transmittance for ultraviolet light of a specific wavelength, making it suitable as a material for allowing ultraviolet light of a specific wavelength to pass through.

[0058] In addition, Figure 1 In the example shown, window 42 is a window made of a material that allows ultraviolet light of a specific wavelength to pass through, and window 41 is a filter window 6 having a substrate made of a material that allows ultraviolet light of a specific wavelength to pass through and an optical filter disposed on the substrate.

[0059] The light source unit 2 is a unit that emits ultraviolet light of a specific wavelength. The light source unit 2 has a light source such as a deuterium lamp that emits ultraviolet light of a specific wavelength and an illumination window 20 that illuminates the window portion 41 with ultraviolet light of the specific wavelength. As an example, the illumination window 20 is configured to be parallel to the surface of the window portion 41. Preferably, the illumination window 20 illuminates the window portion 41 with ultraviolet light of the specific wavelength in a manner where the light path L is perpendicular to the surface of the window portion 41.

[0060] The light source of light source unit 2 does not need to be a light source capable of emitting all wavelengths of ultraviolet light in a specific wavelength band (having a continuous spectrum in the specific wavelength band), but is preferably a light source that emits light in a wavelength band with a bandwidth of at least 100 nm (a half-width at half-maximum of 50 nm) in the specific wavelength band. Besides deuterium lamps, examples of such light sources include non-single-wavelength LED light sources and xenon lamps such as mercury-xenon lamps. The light source of light source unit 2 is preferably a light source that continuously includes light in the wavelength range of 115 nm to 320 nm, that is, preferably a light source with a continuous spectrum in the wavelength range of 115 nm to 320 nm. Furthermore, light source unit 2 may also be a unit that emits light including wavelengths other than the specific wavelength band (e.g., light in a wavelength band adjacent to the specific wavelength band). Furthermore, when the target gas contains a specific component, the light source for light source unit 2 can be a light source with a single wavelength in a specific wavelength band. Examples include a light source with bright-line spectral emission characteristics like a laser light source, a light source that extracts only a specific wavelength using an optical filter, or a narrow-band light source with a bandwidth of approximately 20 nm (half-width at half maximum of 10 nm) in a specific wavelength band. In this case, the absorption wavelength of the target component overlaps with the wavelength of the light source.

[0061] The light source unit 2 can irradiate the window 41 with ultraviolet light of a specific wavelength emitted from the illumination window 20 through the condenser lens 7. The condenser lens 7 is an optical structure that refracts the incident light to make it parallel or converge to a focal point. The condenser lens 7 can be a single lens or an optical structure composed of multiple lenses and reflectors. When the condenser lens 7 is a single lens, it can be formed of a material that allows ultraviolet light of a specific wavelength to pass through, such as MgF2 (magnesium fluoride).

[0062] The light source unit 2 allows ultraviolet light of a specific wavelength emitted from the illumination window 20 to be incident on the condenser lens 7, and to irradiate the window portion 41 with ultraviolet light of the specific wavelength focused by the condenser lens 7. The condenser lens 7 is preferably a lens in which the focal point of the ultraviolet light of the specific wavelength focused by the condenser lens 7 is located at the light receiver 3 (described later). This improves the light-receiving sensitivity of the light receiver 3.

[0063] The light receiver 3 is a sensor device that has a photoelectric conversion function, which receives transmitted light and converts it into electrical signals such as voltage and current corresponding to the intensity of the received transmitted light, and then sends them to the control unit C, which includes an analysis device such as an AD converter and a computer. One example of the light receiver 3 is a sensor device equipped with a photomultiplier tube.

[0064] After passing through the filter window 6, the transmitted light containing only specific wavelengths is incident on the light receiver 3. This improves the light receiving sensitivity of the light receiver 3 and reduces noise (improving noise immunity, i.e., increasing the signal-to-noise ratio).

[0065] The light receiver 3 does not necessarily need to be a light receiver capable of detecting the spectrum of transmitted light or emitting a signal corresponding to the spectrum. The light receiver 3 only needs to be able to receive transmitted light in a specific wavelength band and emit a signal corresponding to the intensity of the received transmitted light. Therefore, the gas concentration measuring device 100 can measure gas concentration with high sensitivity. Furthermore, the light receiver 3 preferably has no sensitivity to wavelengths other than the specific wavelength band. The light receiver 3 preferably has sensitivity across the entire wavelength band from 115 nm to 320 nm.

[0066] The light receiver 3 is more preferably sensitive in the band that the filter window 6 allows to pass through (the transmission band) and not sensitive in other bands. Thus, the gas concentration measuring instrument 100 can perform gas concentration measurement while achieving both higher sensitivity and higher noise immunity.

[0067] When the light receiver 3 is a photomultiplier tube, the light receiver 3 has a light guide window 30 that guides the transmitted light into the tube. As an example, the light guide window 30 is configured to be parallel to the surface of the window portion 42. The light guide window 30 is preferably configured to intersect the light path L perpendicularly.

[0068] Furthermore, no beam splitter is provided between the light source unit 2 and the light receiver 3, that is, on the optical path L. In other words, in the gas concentration measurement method according to this embodiment, beam splitting is not performed during the light receiving process of the light receiver 3.

[0069] The illumination window 20, condenser lens 7, window portion 41, tube portion 10, window portion 42 (filter window 6), and light guide window 30 are arranged in this order, overlapping each other along the light path L (i.e., on the light path L). Furthermore, in this embodiment, it is permissible to use components such as reflectors to refract the light path L. Figure 1 As shown, the axial direction of the cylinder 10 is preferably arranged along the optical path L. This allows ultraviolet light of a specific wavelength to travel a longer distance through the gas being measured, thus improving the sensitivity of the gas concentration measuring instrument 100 during measurement.

[0070] The illumination window 20 and the window portion 41 do not abut against each other; they are simply positioned at a certain distance. If a condenser lens 7 is to be installed, it can be positioned between the illumination window 20 and the window portion 41. The illumination window 20 and the condenser lens 7 are simply positioned at a certain distance. Similarly, the condenser lens 7 and the window portion 41 are also positioned at a certain distance. Likewise, the window portion 42 and the light guide window 30 do not abut against each other; they are simply positioned at a certain distance.

[0071] The first container 51 is a container that surrounds the space containing the light path L of ultraviolet light of a specific wavelength between the light source unit 2 and the chamber 1. The first container 51 is made to be a vacuum inside the container, or to be in a state where a specific gas is sealed inside the container or a specific gas is allowed to circulate inside the container, thereby preventing gases other than the specific gas from entering the outside of the container, thus controlling the internal atmosphere to be a vacuum or a state filled with the specific gas.

[0072] The first container 51 is fixed to a base on which the light source unit 2 and the chamber 1 are mounted, and is preferably detachable. The first container 51 is preferably formed of a material, for example, metal, that prevents light (especially ultraviolet light of a certain wavelength) from passing through.

[0073] When a specific gas is sealed inside the first container 51 or when a specific gas flows through the container, this specific gas is preferably a non-interfering gas. This non-interfering gas is a gas that does not have an absorption wavelength that overlaps with the component being measured in a specific wavelength band, particularly a gas that does not have an absorption wavelength between 130 nm and 320 nm. By sealing the first container 51 with a non-interfering gas or allowing it to flow through the container, thus filling the first container 51 with the non-interfering gas, attenuation caused by absorption other than that caused by the component being measured within the chamber 1 can be suppressed. That is, attenuation of the specific wavelength ultraviolet light in the specific wavelength band on the optical path L between the light source unit 2 and the chamber 1 can be suppressed. Therefore, the sensitivity of the gas concentration measuring instrument 100 during measurement is improved.

[0074] The first container 51 only needs to be able to enclose at least the space containing the light path L between the illumination window 20 and the incident portion 11, but it can also enclose a space beyond that range. The first container 51 preferably encloses the space containing the illumination window 20, the light path L between the illumination window 20 and the incident portion 11, and the space of the incident portion 11 (the end of the chamber 1 on the side of the light source unit 2). In this way, it is possible to reliably make the space containing the light path L between the illumination window 20 and the incident portion 11 a vacuum or fill it with a non-interfering gas. Figure 1 The diagram shows the first container 51, which includes the incident section 11, the condenser lens 7, and the light source unit 2, and surrounds them.

[0075] The second container 52 is a container that surrounds the space containing the optical path L of ultraviolet light of a specific wavelength between the chamber 1 and the photodetector 3. The second container 52 makes the interior of the container a vacuum, or makes the interior of the container sealed with a specific gas or allows a specific gas to circulate inside the container, thereby preventing gases other than the specific gas from entering the exterior of the container, thus controlling the internal atmosphere to a vacuum or a state filled with a specific gas.

[0076] The first container 51 is fixed to a base containing the chamber 1 and the photodetector 3 as needed, and is preferably detachable. The first container 51 is preferably formed of, for example, a material that prevents light (especially ultraviolet light of a certain wavelength) from passing through, such as metal.

[0077] Similar to the first container 51, the second container 52 is filled with non-interfering gas. This improves the sensitivity of the gas concentration measuring device 100 during measurement.

[0078] The second container 52 only needs to be able to enclose at least the space containing the optical path L between the emission section 12 and the light guide window 30, but it can also enclose a space beyond that range. The second container 52 preferably encloses the space containing the emission section 12, the optical path L between the emission section 12 (the end of the emission section 1 on the light receiver 3 side of the chamber 1) and the light guide window 30, and the space containing the light guide window 30. This ensures that the space containing the optical path L between the emission section 12 and the light guide window 30 can be reliably made a vacuum or filled with a non-interfering gas. Figure 1 The second container 52 is shown as including the emission section 12 and the light guide window 30, which are surrounded by the second container 52.

[0079] Examples of non-interfering gases include nitrogen, hydrogen, helium, argon, or carbon dioxide. Nitrogen, hydrogen, or carbon dioxide do not have absorption wavelengths in specific wavelength ranges and are readily available at low cost. The non-interfering gas is particularly preferably the same type as the carrier gas. If the non-interfering gas is the same type as the carrier gas, even if gas leaks from inside the first container 51 or the second container 52 into the chamber 1, the impact on the gas being measured can be minimized. In particular, when the gas concentration measuring device 100 is used in a series measurement, the impact on the downstream manufacturing process can be minimized.

[0080] In the gas concentration measuring instrument 100 described above, the concentration of the target component in a target gas formed by mixing a target component having an absorption wavelength in a specific wavelength band with a carrier gas that does not have an absorption wavelength in the specific wavelength band can be measured in the following manner. This measurement can be performed according to the following steps.

[0081] First, the gas to be measured is circulated through chamber 1 (an example of the circulation process), and ultraviolet light of a specific wavelength is irradiated onto the gas to be measured flowing through chamber 1 from light source unit 2 through condenser lens 7 and window 41 (an example of the irradiation process). Then, the transmitted light that has passed through the gas to be measured is received by light receiver 3 through window 42 (an example of the light receiving process).

[0082] At this time, the condenser lens 7 is used to focus the ultraviolet light of a specific wavelength irradiated by the light source unit 2 and irradiate the gas to be measured, thereby improving the light-receiving sensitivity of the light receiver 3.

[0083] At this time, by setting window 41 or window 42 as a filter window 6 (an example of a filtering process), a specific wavelength can be selected for the photodetector 3 to receive light, thereby reducing the noise of light received by the photodetector 3 (improving noise immunity, i.e., improving the signal-to-noise ratio). For example, when window 42 is set as a filter window, the light emitted within the chamber 1 (e.g., light emitted by ultraviolet light of a specific wavelength) or light incident on the chamber 1 from a light source other than the light source unit 2 can be blocked by window 42 as a filter window, thus reducing the noise of light received by the photodetector 3. Furthermore, when window 41 is set as a filter window, the decomposition or emission of the measured object component within the chamber 1 caused by ultraviolet light of a specific wavelength can be reduced, thereby reducing the noise of light received by the photodetector 3.

[0084] Furthermore, at this time, no beam splitter is configured on the optical path L or the light receiver 3 does not have a beam splitting function. This can improve the light receiving sensitivity of the light receiver 3 and reduce noise.

[0085] Furthermore, at this time, the optical path L (excluding the chamber 1) for ultraviolet light of a specific wavelength band is made into a vacuum or filled with a non-interfering gas that does not have an absorption wavelength that overlaps with the component being measured in the specific wavelength band. This suppresses the attenuation of transmitted light after passing through the gas being measured due to reasons other than absorption by the gas being measured, thereby improving the light-receiving sensitivity of the photodetector 3 and reducing noise (improving the signal-to-noise ratio). Additionally, the non-interfering gas is preferably a gas of the same type as the carrier gas. For example, the carrier gas and the non-interfering gas are preferably nitrogen, hydrogen, helium, or argon, which do not have an absorption wavelength in the specific wavelength band.

[0086] The target gas is preferably composed of a single type of component. By setting the target component to a single type, measurements with high sensitivity, strong noise immunity, and high signal-to-noise ratio can be performed.

[0087] Furthermore, in the gas concentration measuring device 100, no spectrometer is used, and the absorption wavelength is not determined based on the spectrometer. Therefore, the measurement sensitivity of the gas concentration measuring device 100 is improved by directly utilizing the light-receiving sensitivity of the light receiver 3. Moreover, in the gas concentration measurement method according to this embodiment, by utilizing the characteristics of the gas concentration measuring device 100, a gas mixture consisting of a component having an absorption wavelength within a specific wavelength band and a carrier gas without an absorption wavelength within that specific wavelength band is used as the measurement target, thereby achieving highly sensitive measurement.

[0088] As described above, the gas concentration measuring device and method according to this embodiment can perform measurements with high sensitivity, strong noise immunity, and high signal-to-noise ratio. Because of this high sensitivity, strong noise immunity, and high signal-to-noise ratio, the gas concentration measuring device and method according to this embodiment are particularly suitable for concentration management of material gases used in semiconductor manufacturing processes, especially for concentration management based on series or parallel measurements. Specifically, the gas concentration measuring device and method according to this embodiment achieve both high sensitivity and high signal-to-noise ratio measurements. Therefore, in the case of material gas concentration management based on series or parallel measurements, precise concentration management and detection of anomalies (unexpected concentration fluctuations) within a short time can be achieved. This allows for rapid feedback of these measurement results to the manufacturing process, thereby contributing to improved manufacturing yield. For example, in measuring devices or methods with low sensitivity and low signal-to-noise ratio, precise concentration management is not possible, and the time required to determine whether the measurement result is an anomaly affected by noise is long, making rapid feedback to the manufacturing process difficult.

[0089] Example

[0090] The following describes the gas concentration measuring device and the gas concentration measuring method based on embodiments.

[0091] (Example 1)

[0092] In this embodiment, a gas concentration measuring device according to the above-described gas concentration measuring device is used, and a mixed gas consisting of a carrier gas N2 (nitrogen) that has no absorption wavelength in a specific wavelength range and a measured component N2H4 (hydrazine) that has an absorption wavelength in a specific wavelength range is mixed as the measured gas. The relationship between the concentration of the measured component in the mixed gas and the voltage from the photodetector is then determined. Furthermore, in this embodiment, the light source of the light source unit uses a light source with a wavelength range of 115 nm to 400 nm (manufactured by Hamamatsu Photonics Co., Ltd., model: L7293). That is, the light from this light source continuously includes light with a wavelength range of 115 nm to 320 nm. In addition, the window of the incident section is a filter window having a transparent substrate formed of magnesium fluoride and an optical filter disposed on the substrate. The optical filter of the filter window uses a filter that allows only vacuum ultraviolet light with a wavelength around 147 nm (center wavelength: 147 nm, bandwidth: 20 nm, transmission band: 137 nm to 157 nm) to pass through, which is the center absorption wavelength of hydrazine (the center wavelength of the band that produces significant absorption). Furthermore, a photodetector equipped with a photomultiplier tube (manufactured by Hamamatsu Photonics Co., Ltd., model: R6836) that is sensitive to light with wavelengths of 115 nm and above to 320 nm is used. The interiors of the first and second containers are configured to be filled with a nitrogen atmosphere, that is, the space of the optical path between the illumination window of the light source unit and the incident part of the chamber, the space of the incident part of the chamber, the space of the exit part of the chamber, and the space of the optical path between the exit part of the chamber and the light guide window of the photodetector are all filled with a nitrogen atmosphere.

[0093] In this embodiment, the concentration of the measured component is varied within the range of 0.1 volume % (hereinafter, volume % is abbreviated as %) to 1.0%, and the corresponding voltage output from the photodetector is measured to obtain the relationship between the concentration of the measured component and the voltage output. Then, the least squares method is applied to process the values ​​of the concentration of the measured component and the voltage output, and an approximate straight line (approximate formula) between the concentration of the measured component and the voltage output is obtained using a linear function. The lower limit of detection, which serves as the sensitivity of the measuring instrument, and Ro, which serves as the noise of the measurement, are then determined. 2 Value (determination coefficient). Furthermore, in this embodiment, the voltage output is obtained by varying the concentration of the measured component at five levels: 0.1%, 0.2%, 0.5%, 0.8%, and 1.0%.

[0094] Figure 2This embodiment shows the concentration of the measured component, its corresponding voltage output, their approximate linear relationship, and R. 2 Value. In Figure 2 In the graph, the solid black dots represent the results of this embodiment. From these results, it can be seen that R... 2 A value exceeding 0.9999 indicates strong noise immunity and a high signal-to-noise ratio for measurements. Furthermore, it is known that the detection limit calculated based on this approximate straight line is 10 ppm (hereinafter abbreviated as ppm), which is sufficiently high a detection sensitivity for practical applications. Additionally, in this embodiment, a detection sensitivity of 20 ppm or higher is considered sufficiently high for practical applications.

[0095] (Example 2)

[0096] The difference between this embodiment and Embodiment 1 is that the measured component is vaporized MoO2Cl2 (molybdenum dichloride), and the optical filter of the measuring instrument's filter window is replaced with a filter that allows only ultraviolet light of a specific wavelength band (center wavelength: 296.7 nm, bandwidth: 40 nm, band: 276.7 nm and above and 316.7 nm and below) to pass through, which is the same as in Embodiment 1. Thus, the lower limit of detection, representing the sensitivity of the measuring instrument, and the R0, representing the noise of the measurement, are obtained. 2 The value. Additionally, the gas mixture used for measurement is prepared by heating solid molybdenum dichlorodioxide to 200°C to vaporize it, and then diluting it with nitrogen. Figure 2 The concentration of the measured component in this embodiment, its corresponding voltage output, their approximate linear relationship, and R are also shown. 2 Value. In Figure 2 In the graph, the white hollow dots represent the results of this embodiment. From these results, it can be seen that R... 2 The value also exceeds 0.9999, enabling measurements with strong noise immunity and a high signal-to-noise ratio. Furthermore, the detection limit is 5 ppm, which, similar to the case in Example 1, provides sufficiently high detection sensitivity for practical applications.

[0097] (Example 3)

[0098] The difference between this embodiment and Embodiment 1 is that the target gas is a mixture obtained by mixing nitrogen (as a carrier gas) with a diluted gas containing 1% by volume of B2H6 (diborane), the target component, obtained by diluting diborane with H2 (hydrogen). Furthermore, the optical filter of the measuring instrument's filter window is replaced with a filter that allows only vacuum ultraviolet light with a wavelength near the center absorption wavelength of diborane (around 125 nm) to pass through (center wavelength: 125 nm, bandwidth: 20 nm, band: 115 nm and above to 135 nm). All other conditions are the same as in Embodiment 1. From this, the lower limit of detection sensitivity of the measuring instrument and the Rnoise of the measurement are obtained. 2 Value. That is, in this embodiment, the gas mixture that is the gas to be measured includes diborane, which is the gas to be measured, and hydrogen and nitrogen, which are the carrier gases. Figure 2 The concentrations of the measured components, their corresponding voltage outputs, their approximate linear relationships, and R0 are also shown in this embodiment. 2 Value. In Figure 2 In the graph, the solid black triangles represent the results of this embodiment. From these results, it can be seen that R... 2 The value also exceeds 0.9999, enabling measurements with strong noise immunity and a high signal-to-noise ratio. Furthermore, the detection limit is 5 ppm, which, similar to the case in Example 1, provides sufficiently high detection sensitivity for practical applications.

[0099] (Example 4)

[0100] The difference between this embodiment and Embodiment 1 is that the measured component is replaced with vaporized IPA (isopropanol), the carrier gas is replaced with CO2 (carbon dioxide), and the optical filter of the measuring instrument's filter window is replaced with a filter that only allows vacuum ultraviolet light with a wavelength around 135 nm (center wavelength: 135 nm, bandwidth: 10 nm, band: above 130 nm and below 140 nm) to pass through. All other conditions are the same as in Embodiment 1. Thus, the lower limit of detection, representing the sensitivity of the measuring instrument, and the Rnoise, representing the measurement noise, are obtained. 2 Value. In addition, in this embodiment, the carrier gas (carbon dioxide) is different from the gas (nitrogen) in the atmosphere inside the first and second containers. Figure 2 The concentrations of the measured components, their corresponding voltage outputs, their approximate linear relationships, and R0 are also shown in this embodiment. 2 Value. In Figure 2 In the graph, the white hollow triangles represent the results of this embodiment. From these results, it can be seen that R... 2The value also exceeds 0.9999, enabling measurements with strong noise immunity and a high signal-to-noise ratio. Furthermore, the detection limit is 5 ppm, which, similar to the case in Example 1, provides sufficiently high detection sensitivity for practical applications.

[0101] (Example 5)

[0102] The difference between this embodiment and embodiment 3 is that a condenser lens is provided between the light source unit and the chamber of the measuring instrument. All other conditions are the same as in embodiment 3. This allows for the determination of the lower detection limit, which serves as the sensitivity of the measuring instrument, and the R0 value, which serves as the noise level of the measurement. 2 value. Figure 2 The concentrations of the measured components, their corresponding voltage outputs, their approximate linear relationships, and R0 are also shown in this embodiment. 2 Value. In Figure 2 In the graph, the white hollow square markers represent the results of this embodiment. From these results, it can be seen that R... 2 The value also exceeded 0.9999, indicating strong noise immunity and a high signal-to-noise ratio for measurements. Furthermore, the detection limit was found to be 1 ppm, which is a higher detection sensitivity than in Example 3.

[0103] (Examples 6 to 8)

[0104] Examples 6 to 8 differ from Examples 1, 2, and 4 in that the first and second containers of the measuring device are not used (removed), and the space between the illumination window containing the light source unit and the incident part of the chamber, and the space between the exit part containing the chamber and the light guide window of the receiver are replaced with the atmospheric environment. Other conditions are the same as in Examples 1, 2, and 4. From this, the detection lower limit value, which serves as the sensitivity of the measuring device, and the R value, which serves as the noise of the measurement, are obtained. 2 value. Figure 3 The concentrations of the measured components in Examples 6 to 8, their corresponding voltage outputs, their approximate linear relationships, and R0 are shown. 2 Value. From these results, we can see that R 2 The value also exceeds 0.9999, enabling measurements with strong noise immunity and high signal-to-noise ratio. Furthermore, it is known that the detection limits of Examples 6 to 8 are 10 ppm, 5 ppm, and 5 ppm, respectively, which are detection sensitivities as high as those of Examples 1, 2, and 4.

[0105] (Comparative Examples 1 to 4)

[0106] The difference between Comparative Examples 1 to 4 and Examples 1 to 4 is that the optical filter of the measuring device was not used, and the window of the exit section was a transparent window made of magnesium fluoride. Other conditions were the same as those in Examples 1 to 4. Figure 4The concentrations of the measured components in these comparative examples, their corresponding voltage outputs, their approximate linear relationships, and R² values ​​are also shown. Figure 4 In the graph, the solid black dots, hollow white dots, solid black triangles, and hollow white triangles represent the curves of the results for Comparative Examples 1 to 4, respectively. The R values ​​for Comparative Examples 1, 2, and 4 are shown below. 2 The value is at most above 0.999, less than 0.9999, and less than the R values ​​of Examples 1, 2, and 4 described above. 2 Value. Furthermore, the R value in Comparative Example 3... 2 The value was 0.99993, which exceeded 0.9999, but was less than the R² value of 0.99997 used in Example 3. Furthermore, the detection limits for Comparative Examples 1 to 4 were 1 ppm, 0.5 ppm, 0.5 ppm, and 1 ppm, respectively.

[0107] (Comparative Example 5)

[0108] The difference between this comparative example and Example 1 is that the optical filter of the measuring instrument is not used, the window of the exit section is a transparent window made of magnesium fluoride, and the first and second containers are removed. The space between the illumination window containing the light source unit and the incident section of the chamber, as well as the space between the exit section containing the chamber and the light guide window of the receiver, are replaced with the atmospheric environment. Other conditions are the same as in Example 1. Therefore, the detection lower limit value as the sensitivity of the measuring instrument and the R value as the noise of the measurement are obtained. 2 value. Figure 5 This embodiment shows the concentration of the measured component, its corresponding voltage output, their approximate linear relationship, and R. 2 Value. From this result, we can see that R... 2 Values ​​below 0.999 become susceptible to noise and result in a low signal-to-noise ratio. Furthermore, the detection limit is at most 100 ppm, which, unlike the examples, indicates lower detection sensitivity.

[0109] As can be seen from the results of the above embodiments and comparative examples, when ultraviolet light of a specific wavelength band is used as a light source for measurement, as in each embodiment, when the gas concentration measuring device and gas concentration measuring method according to this embodiment are provided, that is, when an optical filter is provided in the optical path of the ultraviolet light of a specific wavelength band between the light source unit and the light receiver, it is possible to perform a measurement with sufficiently high sensitivity, strong noise resistance and high signal-to-noise ratio in practical applications.

[0110] In particular, higher detection sensitivity was obtained in Example 5 than in Example 3, which suggests that the condenser lens contributed to the improved sensitivity.

[0111] In particular, considering the results of Examples 6 to 8 in conjunction with the results of Comparative Example 5, the following conclusions can be drawn. In Examples 6 to 8, the first and second containers were removed, and the space between the illumination window of the light source unit and the incident portion of the chamber, and the space between the exit portion of the chamber and the light guide window of the receiver, became an atmospheric environment. Therefore, it can be considered that the ultraviolet light of a specific wavelength band from the light source unit (especially vacuum ultraviolet light in the band around 125 nm) was partially absorbed by oxygen and water in the atmosphere. However, hydrazine, molybdenum dichlorodioxide, and isopropanol, which were the objects of measurement in these examples, do not have strong absorption wavelengths around 125 nm. Therefore, even with the first and second containers removed, the ultraviolet light in the absorption band of hydrazine, molybdenum dichlorodioxide, and isopropanol would not be attenuated in the optical path. Moreover, when an optical filter was provided in the optical path of the ultraviolet light of a specific wavelength band between the light source unit and the receiver, ultraviolet light in bands other than the absorption bands of hydrazine, molybdenum dichlorodioxide, or isopropanol was cut off. Therefore, even when components such as hydrazine, molybdenum dioxide, and isopropanol, which do not have absorption wavelengths that overlap with atmospheric oxygen and water, are used as the components to be measured, measurements with sufficiently high sensitivity, strong noise immunity, and high signal-to-noise ratio can still be performed in practical applications, even if the first and second containers are removed.

[0112] As described above, a gas concentration measuring instrument and a gas concentration measuring method are provided that improve the sensitivity of measurement when using ultraviolet light of a specific wavelength as the light source for measurement.

[0113] [Other Implementation Methods]

[0114] (1) In the above embodiment, the following situation was described: in the gas concentration measuring device 100, the chamber 1 has a cylindrical portion 10 with a straight internal space, and an incident portion 11 and an exit portion 12 provided at the end of the cylindrical portion 10. In the chamber 1, the gas to be measured flows through the cylindrical portion 10, and ultraviolet light of a specific wavelength introduced from the incident portion 11 passes through the gas to be measured and is led out of the chamber 1 from the exit portion 12. However, the shape of the gas concentration measuring device 100 and its chamber 1 is not limited to this.

[0115] For example, chamber 1 can be formed as a transparent substrate that allows ultraviolet light of a specific wavelength to pass through. In this case, the transparent substrate can be formed of magnesium fluoride. Alternatively, chamber 1 can also be a so-called MEMS (Micro Electromechanical Systems).

[0116] One method for forming a gas concentration measuring device 100 using the chamber 1 as a MEMS is as follows: A microflow path for the gas to be measured can be formed within a transparent substrate serving as the chamber 1. Furthermore, if ultraviolet light of a specific wavelength is irradiated from one side of the chamber 1 via a light source unit 2 along the light path that passes through the microflow path, and the transmitted light is received by a photodetector 3 on the other side of the chamber 1, the concentration of the component to be measured can be measured.

[0117] In this case, the illumination window 20 of the light source unit 2, the entire chamber 1, and the light guide window 30 of the light receiver 3 can be covered by a container, thereby surrounding the light path L of the ultraviolet light of a specific wavelength between the light source unit 2 and the chamber 1, as well as the light path L of the ultraviolet light of a specific wavelength between the chamber 1 and the light receiver 3, thereby controlling the internal atmosphere of the container to a vacuum state or a state filled with a specific gas.

[0118] As described in the above embodiments, since the gas concentration measuring device and gas concentration measuring method according to this embodiment can improve the sensitivity during measurement, even if the flow path of the target gas in chamber 1 is miniaturized and the optical path of ultraviolet light passing through a specific wavelength of the target gas is shortened, practical measurement accuracy can still be guaranteed. That is, the gas concentration measuring device and gas concentration measuring method according to this embodiment are applicable to both large-scale applications where the target gas flows horizontally as required in series measurements, and small-scale applications such as those referred to as MEMS.

[0119] (2) In the above embodiments, such as Figure 1 The diagram illustrates a configuration in the gas concentration measuring device 100 where the condenser lens 7 is positioned on the optical path L of ultraviolet light in a specific wavelength band between the light source unit 2 and the chamber 1. It also illustrates a configuration where the illumination window 20, the condenser lens 7, and the window portion 41 are arranged in sequence along the optical path L, overlapping with the optical path L, with the condenser lens 7 and the window portion 41 spaced apart by a certain distance. However, the configuration of the condenser lens 7 is not limited to this example.

[0120] For example, such as Figure 6 As shown, in the gas concentration measuring device 100, the window 41 can also function as a condenser lens 7. Furthermore, Figure 6 The case where window 42 is a filter window 6 is further shown. By making window 41 also serve as a condenser lens 7, the gas concentration measuring instrument 100 can be miniaturized.

[0121] (3) In the above embodiments, such as Figure 1 , Figure 6As shown, at least one of window portion 41 and window portion 42 has a substrate (window) formed of a material capable of transmitting ultraviolet light of a specific wavelength and a filter window 6 with an optical filter disposed on the substrate. However, the optical filter does not necessarily need to be disposed on window portion 41 or window portion 42. The optical filter only needs to be disposed on the optical path L of the ultraviolet light of a specific wavelength between the light source unit 2 and the light receiver 3.

[0122] (4) In the above embodiments, such as Figure 1 As shown, in the gas concentration measuring device 100, the illumination window 20, the condenser lens 7, and the window portion 41 are arranged in sequence along the light path L, overlapping with the light path L. Furthermore, the example described is a filter window 6 with a substrate made of a material capable of transmitting ultraviolet light of a specific wavelength and an optical filter disposed on the substrate. However, the arrangement of the optical filter is not limited to these examples. For example, the optical filter may be arranged between the illumination window 20 and the condenser lens 7. That is, the illumination window 20, the optical filter, the condenser lens 7, and the window portion 41 without the optical filter may be arranged in sequence along the light path L, overlapping with the light path L.

[0123] Furthermore, the embodiments disclosed in this specification are merely examples, and the embodiments disclosed herein are not limited thereto. Appropriate modifications may be made without departing from the purpose of this disclosure.

[0124] (Industrial applicability)

[0125] This disclosure can be applied to gas concentration measuring instruments and gas concentration measuring methods.

[0126] (Explanation of the labels in the attached diagram)

[0127] 1: Chamber; 10: Cylinder; 100: Gas concentration measuring device; 11: Injection section; 11a: Base;

[0128] 11b: Cover; 12: Ejector section; 12a: Base; 12b: Cover; 15: Inlet; 16: Outlet;

[0129] 2: Light source unit (light source); 20: Illumination window; 3: Light receiver; 30: Light guide window; 41: Window section;

[0130] 42: Window section; 51: First container; 52: Second container; 6: Filter window; 7: Condenser lens; C: Control section;

[0131] L: Optical path.

Claims

1. A gas concentration measurer, wherein, It possesses: A chamber through which the gas containing the measured component and the carrier gas flows; A light source that irradiates the gas to be measured in the chamber with ultraviolet light having a wavelength between 115 nm and 320 nm. A light receiver that receives transmitted light through the ultraviolet light emitted by the gas being measured; and An optical filter is disposed in the optical path of the ultraviolet light between the light source and the light receiver. The optical filter allows only specific wavelengths of the ultraviolet light to pass through.

2. The gas concentration measuring device according to claim 1, wherein, The gas concentration measuring device also includes a focusing lens disposed in the optical path of the ultraviolet light between the light source and the chamber.

3. The gas concentration measuring device according to claim 1 or 2, wherein, The gas concentration measuring device also includes: A first container encloses a space containing the optical path of the ultraviolet light between the light source and the chamber; and The second container surrounds the space containing the optical path of the transmitted light between the chamber and the photoreceptor. The first and second containers are either made into a vacuum, or filled with a non-interfering gas, which is a gas that does not have an absorption wavelength that overlaps with the component being measured in the ultraviolet light band.

4. The gas concentration measuring device according to claim 3, wherein, The non-interfering gas is the same type of gas as the carrier gas.

5. The gas concentration measuring device according to claim 3, wherein, The non-interfering gas is nitrogen, hydrogen, helium, or argon.

6. The gas concentration measuring device according to claim 1 or 2, wherein, The ultraviolet light continuously includes light with wavelengths ranging from 115 nm to 320 nm. The optical filter allows a bandwidth of 5nm or more and 50nm or less for the transmitted wavelength band.

7. A method of measuring the concentration of a gas, wherein, It includes: The flow process involves passing a carrier gas that does not have an absorption wavelength in the ultraviolet light band with wavelengths above 115 nm and below 320 nm, and a measurement target gas formed by mixing the measurement target component that has an absorption wavelength in the ultraviolet light band, through a chamber. An irradiation process, wherein the gas to be measured is irradiated with ultraviolet light flowing through the chamber; and The light-receiving process involves receiving transmitted light from the ultraviolet light that has passed through the gas being measured. The irradiation process or the light-receiving process includes a filtering process that selects a specific wavelength band.

8. The gas concentration measurement method according to claim 7, wherein, In the irradiation process, the ultraviolet light is focused and used to irradiate the gas to be measured.

9. The gas concentration measurement method according to claim 7 or 8, wherein, The optical path of the ultraviolet light is made into a vacuum, or the optical path of the ultraviolet light is filled with a non-interfering gas, wherein the non-interfering gas is a gas that does not have an absorption wavelength that overlaps with the component of the measured object within the ultraviolet light band.

10. The gas concentration measurement method according to claim 9, wherein, The non-interfering gas is the same type of gas as the carrier gas.

11. The gas concentration measurement method according to claim 9, wherein, The non-interfering gas is nitrogen, hydrogen, helium, or argon.

12. The gas concentration measurement method according to claim 7 or 8, wherein, The ultraviolet light continuously includes light with wavelengths ranging from 115 nm to 320 nm. The bandwidth of the selected band in the filtering process is above 5nm and below 50nm.

13. The gas concentration measurement method according to claim 7 or 8, wherein, The gas being measured contains impurity gases that do not absorb wavelengths within the ultraviolet light band.

14. The gas concentration measurement method according to claim 7 or 8, wherein, The gas being measured contains a single type of component.

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