System having gas analyzer and control method thereof

Abstract

To provide a device capable of accurately analyzing a trace component with a simple mechanism.SOLUTION: A system 100 having an analyzer 1 for analyzing components contained in a gas 9 is provided. The analyzer includes a filter 25 for selecting and passing components contained in the gas, a detector 26 for detecting the components passed through the filter, and a first control device 36 configured to set the filter 25 so that the detector 26 detects an isotopic 20Ne having a low abundance ratio instead of an isotopic 21Ne having a high abundance ratio.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a system having a gas analyzer and a control method thereof. [Background technology]

[0002] Patent Document 1 describes a real-time GC / MS trace gas detection and analysis system that captures and accumulates a trace gas sample, leaves the sample for delivery to a GC column for separation, separates the sample into sample components through the GC column, and analyzes all of the sample components in real time with a mass spectrometer. In this system, a gas flow distribution system accumulates the sample from a sample-bearing carrier gas in a micro-accumulator, delivers it to a gas chromatography column using a carrier gas, and supplies the carrier gas to the gas chromatography column to facilitate separation of the sample into sample components in real time and transport the sample components to a mass spectrometer for trace gas detection and analysis or testing.

[0003] Patent Document 2 discloses a rare gas (e.g., krypton) recovery system that can recover and purify rare gas from exhaust gas containing 100 ppm to 1% (preferably a maximum volume concentration of less than 500 ppm) of rare gas discharged from semiconductor manufacturing equipment. This system includes an impurity removal unit that removes predetermined impurities from the rare gas-containing exhaust gas, a rare gas separation membrane module that separates the rare gas into a concentrated exhaust gas containing a high-concentration rare gas (krypton) with a higher rare gas concentration than the rare gas-containing exhaust gas from which the predetermined impurities have been removed, and an exhaust gas with a low rare gas concentration, and a rare gas adsorption unit that selectively adsorbs the rare gas from the concentrated exhaust gas.

[0004] Patent Document 3 describes the provision of a laser gas recycling system and method capable of obtaining purified gas from exhaust gas discharged from an excimer laser oscillator by removing predetermined impurities. This laser gas recycling system is for removing predetermined impurities from exhaust gas discharged from an excimer laser oscillator or an oscillation chamber of an excimer laser to obtain purified gas mainly composed of high-purity neon gas, and includes a separation membrane device that separates excitation rare gases other than neon from the gas to be treated through membrane separation, and an impurity removal device that removes predetermined impurities from the treated gas that has permeated (or not permeated) through the separation membrane device.

[0005] Patent Document 4 discloses a two-stage ArF excimer laser exposure apparatus that operates at an oscillation frequency of 4 kHz or more and includes an oscillation laser apparatus having an oscillation chamber filled with a first laser gas containing F2 gas, Ar gas, and a first buffer gas, and an amplifier having an amplification chamber filled with a second laser gas containing F2 gas, Ar gas, and a second buffer gas, and that amplifies and emits the laser beam emitted from the oscillation laser apparatus, wherein the first buffer gas is He gas or a mixed gas of He gas and Ne gas, and the second buffer gas is Ne gas. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-145295 [Patent Document 2] Patent Publication No. 2021-154240 [Patent Document 3] Japanese Patent Application Publication No. 2019-141752 [Patent Document 4] Japanese Patent Application Laid-Open No. 2005-123528 Summary of the Invention [Problem to be solved by the invention]

[0007] Many processes use gases containing both the main component and trace components, ranging from a few percent to ppm or even sub-ppm (ppb) levels. Many applications require highly accurate determination of the trace component content. Gas lasers are one example, and well-known lasers include helium-neon lasers, argon lasers, krypton lasers, carbon dioxide lasers, and excimer lasers. Excimer lasers, which generate laser light using a mixture of rare gases and halogens, are widely used in machining, semiconductor manufacturing, and ophthalmic treatment. In gas lasers and other processes, there is a constant need to monitor the composition of the gases being used in the process (including gases supplied to the process, gases generated during the process, gases emitted from the process, and by-product gases, hereafter referred to as process gases) to improve product yield and precision. This monitoring is essential for managing the process and the equipment (processing equipment) that performs the process.

[0008] Furthermore, from the perspectives of resource conservation and circular economy, there is an increasing demand for the reuse of gases used in processes that are discarded (exhausted) or contain impurities. Even in such processes, there is a strong demand for monitoring the gas composition at each stage of the recovery and / or regeneration process. Conventional instruments for measuring trace components in gases, such as GC / MS, are large, take time to measure, and consume carrier gases such as helium. Therefore, there is a demand for an instrument and method that can accurately analyze trace components on-site using a simple mechanism. [Means for solving the problem]

[0009] One aspect of the present invention is a system including an analyzer for analyzing components contained in a gas. The analyzer includes a filter that selectively passes components contained in the gas, a detector that detects the components that have passed through the filter, and a first control device configured to set the filter so that the detector detects at least one of the isotopes of the first component that is less abundant as a first component contained in the gas, instead of the isotope of the first component that is more abundant. The first control device may set the filter so that only one of the isotopes of the first component that is less abundant is detected by the detector.

[0010] When the first component is the main component or one of the main components of the gas being analyzed, the detection intensity will be several to several tens, hundreds, or even more times that of the trace component, making it difficult to measure the first component and the trace component with the same degree of precision. On the other hand, the detection intensity of the isotope of the first component with a low abundance will be several times, several tens, or several hundreds times lower than the detection intensity of the isotope of the first component with a high abundance. For this reason, in the past, isotopes with a high abundance were the main target of measurement, and isotopes with a low abundance were difficult to measure because they were buried in noise, or were not of particular interest in measurements.

[0011] In the present invention, instead of the isotope of the first component with a high abundance, i.e., without measuring (detecting) the isotope of the first component with a high abundance, at least one of the isotopes of the first component with a low abundance or at least one of the isotopes of the first component with a low abundance is selected by a filter and measured (detected) by a detector. This allows for the measurement of trace components, which are a fraction, several tenths, or several hundredths of the major component, or even less, with the same or similar accuracy as the major component, the first component. This allows for the accurate measurement of components contained in a gas, including trace components, and allows for accurate analysis of the gas components. Furthermore, since there is no need to detect a very high intensity signal corresponding to the major component, detector degradation can be suppressed.

[0012] The controller may include a second control device (second coordination function, second coordination device, second coordination control device) that selects a second component contained in the gas using a filter with a resolution lower than the resolution for selecting one of the isotopes of the first component with a lower abundance ratio and detects it with a detector. If the second component is even less abundant, the detection intensity of the second component can be increased by lowering the resolution of the filter for the component with a higher intensity. Therefore, even if the content of the second component is even lower than the content of the isotope of the first component with a lower abundance ratio, the second component, which is a minor component, and the first component, which is a major component, can be measured with the same or similar accuracy via the isotope of the first component with a lower abundance ratio.

[0013] The analyzer may have an ionizer that ionizes components contained in the gas upstream of the filter. The ionizer may have an ionization energy set to suppress ionization of the first component. This can suppress saturation of the ion source in the analyzer due to ionization of the first component, which has a high abundance ratio, and suppress the influence on the measurement of other trace components, including impurities. The analyzer may also include a third control device that sets the ionization energy of the ionizer to suppress ionization of the first component. An example of an ionizer includes a filament that emits thermal electrons.

[0014] The system may include a chamber configured to temporarily hold the gas upstream of the analyzer, and an exhaust system configured to control the amount of gas flowing into the chamber. Further, the exhaust system may be configured to maintain a pressure P in the chamber at condition (1) below: 0.005Pa <P<0.05Pa···(1) The lower limit of condition (1) may be 0.008, and the upper limit may be 0.03.

[0015] The pressure of the gas introduced into a mass spectrometer that filters by mass-to-charge ratio (m / z) is 10 mPa (10 -3By controlling the pressure to below 100 Pa, the influence of components with high abundances (abundance ratios) is often suppressed. In this system, isotopes of the first component, which has the highest abundance (abundance ratio), are not measured, but isotopes of the first component with low abundance ratios are measured. Furthermore, it is possible to suppress ionization of the main first component. Therefore, although increasing the pressure in the chamber increases the abundance of the main first component and trace components in the chamber, the measurement is less affected by the increase in the main first component. Therefore, by increasing the pressure in the chamber, the abundance of the trace components increases, which can result in increased measurement (detection) sensitivity for trace components.

[0016] An example of the first component is an inert gas such as neon (Ne) or argon (Ar). Inert gases have high ionization energy. This makes it easy to set an ionization energy that suppresses the ionization of the major component while minimizing the ionization of trace components. Furthermore, increasing the pressure in the chamber only increases the amount of inert components, reducing the possibility of deterioration of the analyzer, such as oxidation of the filament. The filter may include a quadrupole filter.

[0017] This system may include a processing device into which process gas flows or is discharged, a supply device that supplies at least one of the input, intermediate, and output process gases of the processing device to an analytical device as a gas to be analyzed, and a management device that manages the processing device and / or the process being performed by the processing device based on the analysis results of the analytical device.

[0018] Another aspect of the present invention is a method for controlling a system including an analyzer that analyzes components contained in a gas. The analyzer includes a filter that selects and passes components contained in the gas and a detector that detects the components that have passed through the filter. The method includes a controller of the analyzer selecting, as a first component contained in the gas, one of the isotopes of the first component that is less abundant using the filter, instead of the isotope of the first component that is more abundant, and detecting the selected isotope with the detector. The controller may also control the analyzer to select only one of the isotopes of the first component that is less abundant using the filter and detect the selected isotope with the detector. The method may further include the controller selecting a second component contained in the gas using the filter with reduced resolution and detecting the selected isotope with the detector.

[0019] The analyzer may include an ionizer that ionizes components contained in the gas upstream of the filter, and the method may further include the controller setting the ionization energy to suppress ionization of the first component. The system may include a chamber that temporarily holds the gas upstream of the analyzer, and an exhaust system that controls the amount of gas flowing into the chamber, and the method may further include the controller maintaining the pressure P in the chamber at the above condition (1).

[0020] The system may include a processing device into which a process gas flows or is discharged, and a supply device that supplies at least one of the input, intermediate, and output process gases of the processing device to an analytical device, and a management device of the system may manage the processing device and / or the process based on the analysis results of the analytical device.

[0021] Another aspect of the present invention is a method for analyzing components contained in a gas using an analytical device. The analytical device has a filter that selectively passes components contained in the gas and a detector that detects the components that have passed through the filter. The method includes selecting, as a first component contained in the gas, either an isotope of the first component that is abundant in a low abundance ratio, instead of an isotope of the first component that is abundant in a high abundance ratio, and detecting the first component with the detector.

[0022] Another aspect of the present invention is a control program (program product) for a system having an analytical device that analyzes components contained in a gas, which may be provided by being recorded on a suitable recording medium. The analytical device has a filter that selects and passes components contained in the gas, and a detector that detects the components that have passed through the filter, and the control program includes instructions for a controller of the analytical device to select, as a first component contained in the gas, one of the isotopes of the first component that is less abundant, instead of the isotope of the first component that is more abundant, as the component that passes through the filter, and detect it with the detector. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a block diagram showing an overview of a system including a gas analyzer. [Figure 2] An example showing the results of gas measurement. [Figure 3] FIG. 10 is a diagram showing how detection intensity changes depending on ionization energy. [Figure 4] FIG. 10 is a diagram showing how the detection intensity changes depending on the chamber pressure. [Figure 5] An example showing the results of gas measurement. [Figure 6] 4 is a flowchart showing an overview of system control. DETAILED DESCRIPTION OF THE INVENTION

[0024] FIG. 1 shows a schematic configuration of a process monitoring system 100 as an example of a system including a gas analyzer 1. The illustrated system 100 is a system that manages a gas regeneration apparatus (recirculation apparatus, processing apparatus) 101 and a gas regeneration process 101p executed by the gas regeneration apparatus 101. The system 100 includes a supply device 102 that switches between or supplies the following process gases to the gas analyzer 1 as a gas to be analyzed (sample gas) 9: gas 109a supplied to the process 101p of the gas regeneration apparatus 101, gas 109b processed and output by the process 101p, and gas 109c being processed in the process 101p; and a management device (process controller) 105 that manages the gas regeneration apparatus 101 and / or process 101p by referring to the analysis results of the gas analyzer 1. The supply device 102 in this example includes switching valves 103a, 103b, and 103c that switch between gases 109a, 109b, and 109c and supply them to the gas analyzer 1.

[0025] The processing equipment that performs a process into or out of which the process gas 109 to be analyzed by the gas analyzer 1 flows is not limited to the gas regeneration equipment 101. The processing equipment may be an equipment for performing a process in a semiconductor process, such as a process for forming various types of films or layers on a substrate or etching a substrate, for example, a process including CVD (Chemical Vapor Deposition) or PVD (Physical Vapor Deposition). The processing equipment is not limited to a process related to semiconductor manufacturing, and may be an equipment for performing a process for depositing various types of thin films on optical components such as lenses and filters as substrates, an equipment for blending, regenerating, or recovering gases used in semiconductor manufacturing, or a processing equipment that handles gases for other purposes.

[0026] An example of the gas regeneration device 101 is disclosed in the aforementioned Japanese Patent Application Laid-Open No. 2019-141752. The gas regeneration device 101 is a device (laser gas recycling system) that obtains purified gas by removing specific impurities from exhaust gas discharged from an excimer laser oscillator. The document describes that an example of the exhaust gas (process gas) 109a to be treated is mainly composed of neon, with rare gases (krypton, xenon, argon) accounting for 1 to 10%, preferably 1 to 8%, of the total, and that impurities in the exhaust gas include, for example, CF4 (CF4), N2 (N2), and He, with the CF4 concentration in the exhaust gas expected to be in the range of 1 ppm to 500 ppm.

[0027] Furthermore, as an example of a laser gas whose main component is neon, Japanese Patent Application Laid-Open Publication No. 2005-123528 discloses a mixed gas such as ArF gas, which contains 3.5% argon (Ar), 10 ppm (0.001%) xenon (Xe), and the remainder neon (Ne), i.e., 96.499%. Therefore, when attempting to monitor the components of the processed gas and the recycled gas by monitoring the device 101 that handles such gas, there is a demand for a gas analyzer 1 that can quantitatively, on-site, and in real time monitor trace components or impurity components that exist at concentrations (mixing ratios) on the order of % to ppm or less relative to the main component.

[0028] The process monitoring system 100 using the gas analyzer 1 of this embodiment monitors the gas 9 to be analyzed in real time and provides highly reliable measurement results (analysis results), thereby enabling innovative process control. For example, the gas analyzer 1 can monitor the gas components used in each process or step involved in semiconductor manufacturing in real time, dramatically improving throughput in semiconductor chip manufacturing and functioning as a total solution platform aimed at maximizing yield rates. Furthermore, by combining it with a system for generating, recovering, and regenerating gases, it can also function as a platform aimed at reviewing each process from the perspectives of resource conservation and the circular economy, and maximizing resource utilization efficiency.

[0029] The gas analyzer 1 of this example is typically a very small mass spectrometer that can be directly connected to or built into the device to be analyzed. The gas analyzer 1 can also be equipped with a standard protocol that is primarily used in semiconductor manufacturing process equipment, such as the EitherCat (registered trademark) protocol 51, and can be integrated into a process equipment control system such as a process monitoring system 100.

[0030] The gas analyzer 1 is an apparatus for analyzing components contained in a gas (sample gas) 9. The gas analyzer 1 includes a chamber 10 configured to temporarily hold the sample gas 9 supplied from the process side by a supply device 102, an ionizer 22 configured to generate ions (ion flow) 17 of the sample gas 9, a filter 25 configured to select and pass components contained in the gas, and a detector 26 configured to detect the components that have passed through the filter. An example of the gas analyzer 1 is a mass spectrometry detector (mass spectrometer, MS). The filter 25 may include a filter unit (typically a mass filter, in this example, a quadrupole filter) 25 that filters (selects, sorts, turns on / off) the ionized sample gas (sample gas ions) 17 supplied from the ionizer 22 based on their mass-to-charge ratio. The detector 26 may also be a detector that detects the filtered ions (ion intensity, ion current).

[0031] The gas analyzer 1 further includes a vacuum container (housing) 40 that houses the filter unit 25 and the detector 26, and an exhaust system 60 that can maintain the interior of the housing 40 and the chamber 10 connected to the housing 40 at an appropriate negative pressure condition (vacuum condition). The chamber 10 is important as a place to control the condition (pressure) of the sample gas 9 flowing into the gas analyzer 1, but its volume should be kept to a minimum, for example, 1 to several tens of cm, to enable real-time measurement. 3 Or 1 to several centimeters 3 The supply device 102 may be a container or buffer having a capacity of about 100 MPa, or may be configured as a part of a pipe that also serves as the supply device 102.

[0032] The exhaust system 60 in this example includes a turbomolecular pump (TMP) 61 and a Roots pump (dry pump) 62, and controls the internal pressure of the chamber 10 via the housing 40, which houses the filter 25 and detector 26. The dry pump 62 may be provided as an option. Other types of pumps may be used in the exhaust system 60, and the system may be a single-stage exhaust system or a multi-stage exhaust system with three or more stages. The exhaust system 60 may also include an exhaust path 65 that bypasses the housing 40 and exhausts the sample chamber 10. The exhaust system 60 may also introduce sample gas 9 into the sample chamber 10 and control the internal pressure of the sample chamber 10, separate from the gas flow rate used for filtering. When analyzing gas to be discarded or exhausted, a large amount of sample gas 9 can be drawn from the process into the sample chamber 10 relative to the amount of gas (ion amount) supplied to the filter 25, providing a gas analyzer 1 capable of monitoring the state (fluctuations) of the process 101p in real time.

[0033] An example of the filter 25 is a mass filter, which includes four cylindrical or columnar electrodes (HyperQuad) 25a whose interiors are hyperbolic to form a hyperbolic electric field for filtering based on mass-to-charge ratio. A quadrupole-type mass filter 25 may have a large number of cylindrical electrodes, for example, nine, arranged in a matrix (array) to form multiple pseudo-hyperbolic electric fields. Examples of the detector 26 include a Faraday cup (FC) and a secondary electron multiplier (SEM). These detectors 26 may be used in combination or in a switchable manner. The detector 26 may also be of other types, such as a channel electron multiplier (CEM) or a microchannel plate (MP).

[0034] The ionization device 22 includes an electron ionization device (filament, EI ion source) 23 that ionizes (electron ionizes) the sample gas 9 supplied from the process 101p via the gas supply device 102 and the chamber 10 by electron impact (thermal electrons). The EI ion source 23 is typically -3 In this example, if the main component of the sample gas 9 is an inert gas, the -2 The gas analyzer 1 can operate in a low vacuum of 0.1 Pa or even lower. The gas analyzer 1 may include one or more lenses (ion lenses, electrostatic ion lenses) 24 configured to direct the ionized gas 9 as an ion flow (ion beam) 17 to a filter 25.

[0035] The gas analyzer 1 includes a controller (control box, control module) 30 that controls each module of the analyzer 1, and an interface device 50 with the outside. The controller 30 includes computer resources such as a CPU and memory, and controls the gas analyzer 1 by loading and executing a program (program product) 39. The program 39 can be provided by being recorded on a computer-readable medium. The interface device 50 includes a power input I / F 52 and an EtherCAT-compliant communication I / F 51.

[0036] The control module (controller) 30 may include a function (ionization control device) 31 for controlling the ionizer 22, a function (filter control device) 32 for controlling the mass filter 25, a function (detector control device) 33 for detecting arriving ions (ion current) using the detector 26, and a function (pressure control device) 34 for controlling the exhaust system 60 to control the pressure in the chamber 10. These control devices 31 to 34 may also have the function of controlling each controlled device (unit) to maintain a set value or condition. The controller 30 may also have a function (cooperative control device) 35 for performing predetermined measurements by cooperatively controlling multiple devices (units) of the gas analyzer 1. For example, the cooperative control device may include a function for setting predetermined conditions in the filter 25 and detecting components selected by those conditions using the detector 26. The ionization control device 31 for controlling the ionizer 22 may also function as an ionization energy control device (filament control device) for controlling the filament current and / or voltage supplied to the filament 23.

[0037] FIG. 2 shows an example of measuring the process gas (first mixed gas) 109b regenerated by the gas regeneration process 101p of the gas regeneration apparatus 101 described above as the sample gas 9. This first mixed gas 109b is ArF gas, and, as an example, contains 3.5% argon (Ar), 10 ppm (0.001%) xenon (Xe), and 96.499% neon (Ne). FIG. 2 shows an example of the results measured when this first mixed gas 109b is used as the sample gas and measured by a conventional mass spectrometer (MS). The results of mass analysis are obtained as intensity versus mass-to-charge ratio (m / z).

[0038] Neon, argon, and xenon are chemically stable inert gases, along with helium and krypton. Neon is an element with atomic number 10, and its stable isotopes are 20Ne (mass-to-charge ratio 20) at 90.48%, 21Ne (mass-to-charge ratio 21) at 0.27%, and 22Ne (mass-to-charge ratio 22) at 9.25%. Argon is an element with atomic number 18, and its stable isotopes are 40Ar (mass-to-charge ratio 40) at 99.6%, 38Ar (mass-to-charge ratio 38) at 0.063%, and 36Ar (mass-to-charge ratio 36) at 0.337%. Xenon is an element with atomic number 54, and its stable isotopes include 132Xe (mass-to-charge ratio 132) which accounts for 26.9%, 131Xe (mass-to-charge ratio 131) which accounts for 21.2%, 130Xe (mass-to-charge ratio 130) which accounts for 4.07%, 129Xe (mass-to-charge ratio 129) which accounts for 26.4%, 128Xe (mass-to-charge ratio 128) which accounts for 1.91%, and 126Xe (mass-to-charge ratio 126) which accounts for 0.089%.

[0039] When this mixed gas 109b is measured using a conventional mass spectrometer, neon accounts for 96% or more of the components contained in the mixed gas 109b, and the concentration (content) of xenon is approximately six orders of magnitude lower than that of neon (10 -6 ) is small. Therefore, it is difficult to simultaneously detect neon and xenon using the same detector under the same conditions. In particular, it is difficult to simultaneously measure each component with high accuracy, and the ion current generated when measuring neon is enormous, making it difficult to ensure the detector's lifespan. Furthermore, even if one attempts to simultaneously measure argon, the ionization of neon, which accounts for the majority of the gas, would saturate the ionizer, inhibiting argon ionization. Therefore, it was thought that it would be impossible to measure such sample gas 9 using a mass spectrometry-type gas analyzer.

[0040] 3, the pressure in the chamber 10 is 10 -2The graph shows an example of the argon intensity obtained when measuring mixed gas 109b while varying the ionization energy (thermal electron energy) of ionizer 22, where Pa is the ionization energy. In conventional mass spectrometers, the ionization energy of the ionizer is set to 70 eV because mass spectra registered in existing databases, including NIST, are measured at 70 eV. However, in this case, as the ionization energy increases, the argon ions increase, but this increasing trend peaks at an ionization energy of approximately 37 eV. Thereafter, as the ionization energy increases toward 70 eV, the argon intensity decreases. Therefore, when the ionization energy exceeds approximately 37 eV, the interior of ionizer 22 is saturated with ionized neon, which accounts for the majority of mixed gas 109b, and argon ionization is inhibited. Therefore, in a gas in which the main component (first component) accounts for several tens of percent, as in this mixed gas 109b, suppressing the ionization of the main component can promote the ionization of other components.

[0041] Figure 4 shows the relationship between the pressure in chamber 10 and the measured argon intensity when the ionization energy was set to 35 eV during measurement of mixed gas 109b. By increasing the pressure in the chamber, more argon is introduced into filter 25, and the intensity measured by detector 26 should increase. This measurement result verified that the measured intensity (detected intensity) of argon increases almost in proportion to the chamber pressure, even when the ionization energy is set lower than the value set in conventional mass spectrometers.

[0042] These inert gas components have relatively high ionization energies: neon has an ionization energy of approximately 21.6 eV, argon has an ionization energy of approximately 15.8 eV, and xenon has an ionization energy of approximately 12.1 eV. Therefore, while ionizing each component at an energy exceeding its ionization energy in the ionizer 22 has the advantage of increasing the amount of ions, excessive ionization can also have adverse effects. In particular, when the ionization energy of the main component (first component) in a gas is high, as in the case of mixed gas 109b in this example, reducing the ionization energy in the ionizer 22 to a predetermined range can suppress ionization of the main component while finding an ionization energy condition that has little effect on the ionization of the trace component. For example, the target ionization energy of the ionizer 22 can be set to a value that is insufficient or insufficient for the ionization energy of the main component (a value that ionizes the main component but not enough to ionize all molecules) and is sufficiently higher than the ionization energy of the trace component.

[0043] The ionization control device 31 of the controller 30 of the gas analyzer 1 of this example may include a function for maintaining the ionization energy of the ionizer 22 at a set value 22a that satisfies the above conditions. The controller 30 may also include a third control device 31a that sets the ionization energy of the ionizer 22 to a value 22a that suppresses ionization of the first component. When the above mixed gas 109b is analyzed as the sample gas 9, the third control device 31a may set the set value 22a of the ionization energy to 35 eV or thereabouts.

[0044] The cooperative control function 35 of the controller 30 includes a first control device 36 configured to set the filter 25 so that the detector 26 detects at least one of the isotopes of the first component having a low abundance ratio, instead of the isotope of the first component having a high abundance ratio, as a first component contained in the gas to be measured (sample gas) 9. The first control device 36 includes a first cooperative function (first cooperative control device) that selects at least one of the isotopes of the first component having a low abundance ratio using the filter 25 and detects it with the detector 26. The first control device 36 may be configured to set the filter 25 so that only one of the isotopes of the first component having a low abundance ratio is detected by the detector 26.

[0045] The controller 30 may further include a second control device 37 that sets the filter 25 so that the detector 26 detects a trace second component contained in the sample gas 9 with a resolution lower than the resolution for selecting an isotope of the first component that is present in a low abundance. The second control device 37 includes a second coordination function (second coordination control device) that selects the trace second component with the filter 25 with a low resolution and detects it with the detector 26.

[0046] The controller 30 may include a pressure control device 34 that maintains the pressure P in the chamber 10 by means of an exhaust system 60 at the following condition: 0.005Pa <P<0.05Pa···(1) The lower limit of condition (1) may be 0.008, and the upper limit may be 0.03.

[0047] 5 shows the results of a simulation of measurement using the gas analyzer 1 of this embodiment with the ArF gas (first mixed gas) 109b as the sample gas 9. First, the first control device 36 sets the filter 25 so that, instead of the isotope (20Ne) with a high abundance ratio of the first component (neon), which is the main component of the sample gas 9, at least one of the isotopes with a low abundance ratio of the first component (21Ne in this example) is selected, without measuring (detecting) the isotope (20Ne) with a high abundance ratio of the first component. At that timing, the detector 26 measures (detects) the ion flow that has passed through the filter 25. The first control device 36 may set the filter 25 so that 20Ne does not pass through (i.e., does not set a timing for passing), or may turn off the detector 26 when 20Ne passes through the filter 25.

[0048] The first control device 36 controls the gas analyzer 1 to use 0.27% (10 -4 ) can be selected by filter 25 and detected by detector 26. As a result, neon, which is the main component of sample gas 9 and accounts for over 90% of the total, can be detected at an intensity close to that of trace components present on the ppm order. Therefore, gas analyzer 1 can accurately measure the components contained in gas 9, including both the main component and trace components, and can accurately analyze the components of gas 9, including the trace components. Furthermore, since gas analyzer 1 does not need to detect extremely strong signals corresponding to the main component, deterioration of detector 26 can be suppressed.

[0049] In the gas analyzer 1 of this example, even in the case of argon, which has the second highest mixture ratio in the ArF gas 109b, the first control device 36 may select only the isotope 36Ar, which has a low abundance ratio, using the filter 25 instead of the isotope 40Ar, which has a high abundance ratio, and detect it using the detector 26. Therefore, in the gas analyzer 1, argon, which has the second highest content in the sample gas 9 after neon, can be detected at the same or similar intensity as the other trace components.

[0050] Furthermore, the gas analyzer 1 uses a pressure control function 34 to set the pressure P within the chamber 10 one order of magnitude or more higher than that of conventional filament-type mass spectrometers, thereby increasing the amount of sample gas 9 flowing into the gas analyzer 1. Meanwhile, the ionization energy control function 31a of the ionization control device 31 lowers the ionization energy setting value 22a to 35 eV, suppressing the ionization of neon isotopes, the main component of the sample gas 9. This allows for a relative increase in the amount of ions of trace components other than neon, thereby improving the detection sensitivity of trace components. Note that the main component of the mixed gas (ArF) 109b to be measured is the inert gas neon, and increasing the flow rate is expected to have little impact on the life of the filament 23. Impurities may originate from the chamber 10 or the supply device 102 to the chamber 10. However, by increasing the amount of gas 9 flowing into chamber 10, the amount of impurities originating from gas regeneration device 101 or process 101p can be increased, which has the advantage of improving the detection sensitivity of trace components that are factors in managing device 101 or process 101p.

[0051] In the gas analyzer 1, the second control device 37 selects a trace amount of the second component (xenon) contained in the sample gas 9 from the process gas (ArF gas) 109b using a filter 25 with a resolution lower than that for selecting an isotope (Ne) of the first component (neon) with a low abundance ratio, and detects the second component with a detector 26. The second control device 37 controls the scan unit (resolution, mass-to-charge ratio m / z) of the gas analyzer 1 so that, when measuring neon, only the Ne isotope is detected with a resolution of 1 AMU or higher. On the other hand, when measuring xenon, the second control device 37 controls the filter 25 and the detector 26 to detect a wide range of xenon isotopes. When measuring xenon, the second control device 37 may also control the filter 25 to use the aggregate (integral) of the measurement results of the detector 26 detected with a resolution of 1 AMU or higher as the xenon detection result. The second control device 37 may set the filter 25 to detect all of the stable isotopes of xenon, 132Xe, 131Xe, 130Xe, 129Xe, 128Xe, and 126Xe, as the intensity of xenon, and detect them with the detector 26.

[0052] These controls and settings enable the gas analyzer 1 to detect xenon, present in the first mixed gas (ArF gas) 109b at ppm-order levels, at an intensity approximately equal to or close to that of nearly 100% neon and a few percent argon. Therefore, the gas analyzer 1 can simultaneously measure, analyze, and monitor trace components in the process gas 109b in real time along with the major components. Similarly, even if the process gas 109 contains impurities, such as helium (He), methane (CH), nitrogen (N), oxygen (O), carbon dioxide (CO), and carbon tetrafluoride (CF), at ppm or sub-ppm (ppb) levels in addition to the components of the intended mixed gas (ArF gas), these impurities can be measured with high accuracy in real time and used for managing the process 101p.

[0053] Furthermore, the system 100 may include a calibration device 70 that calibrates the detection intensity of trace components such as argon and xenon and the detection intensity of the major component, neon, by measuring a standard gas (test gas) 71 containing known concentrations in advance while the measurement conditions of the gas analyzer 1 are set as described above. The controller (control module) 30 of the gas analyzer 1 may also include a mixture ratio output device (computing function, computing device, output device) 38 that stores the calibration results 38a and, when measuring the sample gas 9 on-site, calculates the mixture ratio of the trace components based on the calibration results 38a from the ratio of the detection intensity of neon, the major component (first component), to the detection intensity of other components. The gas analyzer 1 can accurately determine trace components or impurities on-site. Therefore, the measurement results (analysis results) of the gas analyzer 1 can be used to control, manage, and monitor the process 101p. The function for calculating the mixture ratio may be implemented in an external device, such as a process controller 105.

[0054] The gas to be measured by the gas analyzer 1 may be another gas, such as KrF gas. A gas containing krypton (KrF gas) is known as a gas for xenon lasers, either in place of or in addition to xenon. Krypton (Kr) is an element with atomic number 36. Its stable isotopes include 86Kr (mass-to-charge ratio 86) at 17.3%, 84Kr (mass-to-charge ratio 84) at 57%, 83Kr (mass-to-charge ratio 83) at 11.5%, 82Kr (mass-to-charge ratio 82) at 11.6%, 80Kr (mass-to-charge ratio 80) at 2.25%, and 78Kr (mass-to-charge ratio 78) at 0.35%. Therefore, even in a system 100 measuring a mixed gas containing ppm to several percent Kr, the gas analyzer 1 of this embodiment can accurately detect and analyze the Kr, including trace amounts of other impurities, in the same way as a mixed gas containing xenon.

[0055] The analysis results of the gas analyzer 1 can be supplied to the process controller 105 via a communication interface 51, such as EtherCAT, of the interface device 50. The analysis results may also be provided to another external device monitoring the process 101p via the cloud. The process controller 105 may include computer resources such as a CPU and memory, and may be operated by a control program (program product) 108. An example of a process 101p controlled and / or monitored by the process controller 105 is a process performed in a processing device 101 into which gases used in a semiconductor process flow or are discharged. At least one of input, intermediate, and output process gases 109a to 109c of the processing device 101 is supplied to the gas analyzer 1 via a supply device 102 and analyzed, and the processing device 101 and the process 101p can be controlled and monitored based on the analysis results.

[0056] FIG. 6 shows an example of a control process (control method, control program) in a process monitoring system 100 including a gas analyzer 1. In step 81, a supply device 102 selects at least one of process gases 109a-109c from the input, intermediate, or output of a processing device 101 into which a process gas flows or is discharged, and supplies the selected process gas to the gas analyzer 1 as a sample gas 9. In step 82, the gas analyzer 1 starts gas analysis. First, in step 83, the gas analyzer 1 sets the ionization energy 22a of the ionizer 22 to a value appropriate for the gas 9 to be measured using the ionization control device (third control device) 31a. In this example, when measuring a mixed gas containing neon as a main component (first component), the ionization energy 22a is set to, for example, 35 eV, which is sufficient to suppress the ionization of neon. Next, in step 84, the gas analyzer 1 sets the pressure in the chamber 10 to a range of condition (1) higher than normal using the pressure control device 34, thereby increasing the amount of trace components supplied to the gas analyzer 1.

[0057] In step 86, when neon, which is the main component (first component) with the highest concentration, is measured, in step 87, first control device 36 selects 21Ne, which is an isotope with a low abundance, using filter 25 and detects it with detector 26 instead of 20Ne, which is an isotope with a high abundance (without measuring 20Ne). Multiple isotopes with low abundance may be selected for detection, but when attempting to detect a main component with an intensity similar to that of a trace component, particularly a component present in an extremely small amount on the order of ppm, only one of the isotopes with low abundance may be selected using filter 25 (limited to one) and detected with detector 26.

[0058] In step 88, when the next highest concentration of argon is measured, in step 89, the first control device 36 selects the less abundant isotope 36Ar using the filter 25 and detects it with the detector 26 instead of the more abundant isotope 40Ar (without measuring 40Ar).

[0059] In step 90, when measuring xenon (second component), which is a trace component, in step 91, second control device 37 selects xenon isotopes with filter 25 at a resolution lower than the resolution for selecting 21Ne or 36Ar, which are isotopes of the main component with low abundance, and detects them with detector 26. For example, filter 25 selects all of xenon isotopes 126Xe, 128Xe, 129Xe, 130Xe, 131Xe, and 132Xe as targets and detects them with detector 26, and the sum (integral value) of these is the measured value of xenon.

[0060] In step 92, the gas analyzer 1 may output a mixing ratio based on the calibration result 38a using the mixing ratio output device 38 to the process controller 105. Furthermore, information on impurities at ppm or sub-ppm levels, such as helium (He), methane (CH4), nitrogen (N2), oxygen (O2), carbon dioxide (CO2), and carbon tetrafluoride (CF4), obtained during the gas analysis process, may be output to the process controller 105. In step 93, the process controller 105, as a process management device, manages the processing device (gas regeneration device) 101 or the process (gas regeneration process) 101p performed by the processing device based on the measurement results (analysis results) of the gas analyzer 1.

[0061] As described above, one embodiment of the present invention provides a method for rapidly analyzing impurities in Ne gas for excimer lasers using the gas analyzer 1. The concentrations of Ar, Xe, Kr, and other elements in Ne gas for excimer lasers must be kept within a certain range. Furthermore, it must be ensured that components unsuitable for lasers, such as N2, O2, and CO, are below a certain concentration. Furthermore, considering the analysis time, space, and carrier gas consumption, it is desirable to directly introduce the Ne gas into a mass spectrometer and measure the impurities in the Ne gas in real time, without using a gas chromatograph (GC) or the like.

[0062] Therefore, it is desirable to improve the analytical sensitivity of Xe and impurities (e.g., N2, O2, CO, CO2, etc. in Ne) in the Ne gas. In the gas analyzer 1, the pressure control device 34 controls the pressure of the gas analyzer 1 normally (e.g., 10 -3 The gas is introduced into the mass spectrometry chamber 10 in a larger amount than the upper limit (for example, 10 Pa). -2 This allows more impurities to be introduced into the mass analysis chamber.

[0063] In particular, impurities such as N2 and O2 are always present in a certain amount as background components in the mass spectrometry chamber, in addition to those originating from Ne gas. Therefore, it is necessary to distinguish whether they originate from the chamber or from Ne gas. By introducing as much Ne gas as possible into the mass spectrometry chamber and increasing the amount of impurities originating from Ne gas relative to the background in the vacuum, it becomes possible to measure the impurity concentration with higher sensitivity. Furthermore, because Ne gas is an inert gas, introducing more gas than usual into the mass spectrometry chamber 10 causes less damage to the filament 23.

[0064] Next, the ionization energy is controlled by the ionization energy control device (third control device) 31a. Simply introducing too much Ne gas into the mass analysis chamber 10 would saturate the ion source with Ne ions, adversely affecting the analytical accuracy of the impurity concentration. For this reason, the ionization energy (the energy generated when thermal electrons emitted from the filament 23 collide with molecules or atoms) is adjusted to suppress the ionization of Ne. In this example, 35 eV is used. Ne requires significantly more energy to ionize than other atoms and molecules, so by adjusting the ionization energy, it is possible to suppress the ionization of Ne alone while sufficiently ionizing other atoms and molecules.

[0065] Furthermore, if there is no possibility that other components overlap with the mass range of the measurement target (e.g., Xe), the second control device 37 performs measurement by prioritizing sensitivity over resolution. Specifically, by thickening the peak, a higher ion intensity can be obtained.

[0066] Furthermore, the first control device 36 suppresses ionization of Ne (20Ne) and uses the isotope 21Ne, thereby reducing the intensity of the Ne peak used for quantification by several orders of magnitude. In excimer laser gases, the concentrations of Xe, Ar, Kr, and other elements in the Ne gas must be maintained within a certain concentration range. However, maintaining these concentrations within a certain concentration range requires accurate monitoring. The first control device 36 can reduce the intensity of the Ne peak used for quantification by several orders of magnitude, thereby approximating the ratio of each peak between Ne, Ar, and Xe (e.g., in the case of ArF laser gas). Similarly, the use of the isotope 36Ar can reduce the intensity of the Ar peak used for quantification by several orders of magnitude. By carefully selecting the isotopes of each component contained in the gas, the peak intensities can be made closer, thereby improving the accuracy of concentration calculations.

[0067] Furthermore, by detecting 21Ne and 36Ar, which are isotopes with low abundance ratios, and calculating the concentration of each component, it is not necessary to detect ions with large peak currents, such as 20Ne and 40Ar, which reduces deterioration of the detector 26 and allows for the provision of a gas analyzer 1 that can be used for a long period of time.

[0068] Furthermore, the mixing ratio output device 38 allows the concentration (mixing ratio) to be calculated from the ratio of the Ne peak intensity to the peak intensity of other components, always using the Ne peak intensity as the reference. Normally, the impurity concentration is calculated directly from the peak intensity. In this case, the peak intensity changes depending on the amount of gas introduced into the mass spectrometer, so when performing quantification in a system where the pressure of the measurement environment changes, it is necessary to keep the amount of gas introduced into the mass spectrometer constant. In this method, by calculating the concentration based on the Ne peak, even if the pressure inside the mass spectrometer changes slightly, this change can be canceled out.

[0069] Although the above describes an example of a mass filter that uses a quadrupole type as filter 25, this filter 25 may be of other types such as TOF, ion trap, Wien filter, etc., as long as it can select, sort, and turn on / off components containing molecules and / or atoms based on their mass-to-charge ratio (m / z).

[0070] Furthermore, while particular embodiments of the present invention have been described above, various other embodiments and modifications may be devised by those skilled in the art without departing from the scope and spirit of the present invention, and such other embodiments and modifications are within the scope of the following claims, which define the present invention. [Explanation of symbols]

[0071] 1 gas analyzer, 9 gases 25 filter, 26 detector, 36 first control device 100 systems

Claims

1. A system having an analyzer for analyzing components contained in a gas, The analyzer includes a filter that selectively passes components contained in the gas; a detector that detects components that have passed through the filter; a first controller configured to configure the filter so that the detector detects at least one of a less abundant isotope of the first component in the gas instead of a more abundant isotope of the first component.

2. In claim 1, The system, wherein the first controller is configured to set the filter such that only any minor isotopes of the first component are detected by the detector.

3. In claim 1 or 2, The system further comprises a second controller configured to configure the filter to detect a second component contained in the gas with the detector at a resolution lower than the resolution for selecting any of the less abundant isotopes of the first component.

4. In any one of claims 1 to 3, The system, wherein the analyzer further comprises an ionizer that ionizes components contained in the gas upstream of the filter, the ionizer having an ionization energy configured to suppress ionization of the first component.

5. In any one of claims 1 to 3, The analyzer includes an ionizer that ionizes components contained in the gas upstream of the filter; and a third controller that sets the ionization energy of the ionizer to suppress ionization of the first component.

6. In claim 4 or 5, The system wherein the ionizer includes a filament that emits thermal electrons.

7. In any one of claims 1 to 6, a chamber configured to temporarily hold the gas upstream of the analyzer; A system comprising an exhaust system for controlling the amount of gas flowing into the chamber, the exhaust system being configured to maintain a pressure P within the chamber at: 0.005Pa<P<0.05Pa

8. In any one of claims 1 to 7, The system, wherein the first component comprises an inert gas.

9. In any one of claims 1 to 8, The system wherein the filter comprises a quadrupole filter.

10. In any one of claims 1 to 9, a processing device into which a process gas flows or is discharged; a supply device that supplies at least one of the process gases at the input, intermediate, and output of the processing device to the analysis device; a management device that manages the processing device or a process being executed by the processing device based on the analysis results of the analysis device.

11. A control method for a system having an analyzer for analyzing components contained in a gas, comprising: The analyzer includes a filter that selectively passes components contained in the gas; a detector that detects components that have passed through the filter; The method includes a controller selecting, using the filter, at least one of an isotope of the first component that is less abundant as the first component contained in the gas, instead of an isotope of the first component that is more abundant, and detecting the selected isotope with the detector.

12. In claim 11, Selecting at least one of the isotopes of the first component that is less abundant using the filter and detecting it with the detector comprises selecting only one of the isotopes of the first component that is less abundant using the filter and detecting it with the detector.

13. In claim 11 or 12, The method further includes the controller selecting a second component contained in the gas with the filter at a resolution lower than the resolution for selecting any of the less abundant isotopes of the first component and detecting it with the detector.

14. In any one of claims 11 to 13, the analyzer has an ionizer that ionizes components contained in the gas upstream of the filter; The method further includes the controller setting an ionization energy to suppress ionization of the first component.

15. In any one of claims 11 to 14, a chamber for temporarily holding the gas upstream of the analyzer; an exhaust system that controls the amount of gas flowing into the chamber; The method further includes the controller maintaining a pressure P in the chamber at: 0.005Pa<P<0.05Pa

16. In any one of claims 11 to 14, The method, wherein the first component comprises an inert gas.

17. In any one of claims 11 to 16, The system includes a processing device into which a process gas is introduced or discharged; a supply device that supplies at least one of the process gases at the input, intermediate, and output of the processing device to the analysis device; The method comprises a management device of the system managing the processing device or a process performed by the processing device based on the analysis result of the analysis device.

18. A method for analyzing components contained in a gas using an analyzer, comprising: The analyzer includes a filter that selectively passes components contained in the gas; a detector that detects components that have passed through the filter; The method includes selecting, as a first component contained in the gas, at least one of an isotope of the first component having a low abundance ratio, instead of an isotope of the first component having a high abundance ratio, using the filter, and detecting the selected isotope with the detector.

19. A control program for a system having an analyzer for analyzing components contained in a gas, The analyzer includes a filter that selectively passes components contained in the gas; a detector that detects components that have passed through the filter; The control program includes instructions for a controller of the analytical device to select, using the filter, at least one of the isotopes of the first component having a low abundance ratio as the first component contained in the gas, instead of the isotope of the first component having a high abundance ratio, and detect it with the detector.

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