Gas analyzer

Abstract

To provide control of a stray potential of a plasma for making it usable as a stable ion source.SOLUTION: A plasma generation device 10 comprises: a chamber 12 which has a dielectric wall structure and into which a sample gas to be measured flows; a RF supply mechanism 13 for generating a plasma in the chamber by means of an electric field and / or a magnetic field via the dielectric wall structure; and a stray potential supply mechanism 16 including a first electrode 17 disposed along an inner surface of the chamber. The RF supply mechanism includes a RF field forming unit 14 which is located in a first direction to the chamber, and the first electrode may include an electrode disposed in a second direction to the chamber.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a plasma generating device having a chamber in which a microplasma is generated. [Background technology]

[0002] Patent document 1 discloses that a plasma processing apparatus includes a reaction chamber containing a reactive gas, a plasma generation unit that converts the reactive gas in the reaction chamber into plasma, an electrode that measures the plasma floating potential of the plasma generated in the reaction chamber, and an electron emission source that applies a negative bias voltage relative to the plasma floating potential. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-204418 A Summary of the Invention [Problem to be solved by the invention]

[0004] In contrast to plasmas used in processing processes such as CVD, or plasmas found in nature, which are found in macro-scale spaces, microplasma is known as a plasma in the fine region (intermediate region) on the boundary between nanospace and plasma, i.e., in the "mesospace." Microplasma includes plasmas on the order of micrometers, but also includes plasmas whose size ranges from a few mm to about 100 μm. Microplasmas of this size are relatively easy to handle compared to those that require special properties or technology such as nano-size, and various applications are being considered. One such application is as an ion source for analytical equipment, and there is a demand for controlling the floating potential of the plasma in order to use it as a stable ion source. [Means for solving the problem]

[0005] One aspect of the present invention is a microplasma generating device. This generating device has a chamber with a dielectric wall structure into which a gas to be turned into plasma flows, an RF supply mechanism that generates plasma in the chamber by an electric field and / or a magnetic field via the dielectric wall structure, and a floating potential supply mechanism including a first electrode arranged along the inner surface of the chamber. In this plasma generating device, high frequency is supplied from outside the chamber to generate plasma, and electrodes are arranged along the inner surface in the microplasma chamber to surround at least a part of the generated microplasma and control the floating potential of the microplasma. If the microplasma is an intermediate size, neither macro-size nor nano-size, the floating potential of the plasma can be controlled by an electrode arranged to cover the periphery or a part of the periphery.

[0006] The RF supply mechanism may include an RF field forming unit disposed in a first direction relative to the chamber, and the first electrode may include an electrode disposed in a second direction relative to the chamber. An example of the chamber may be cylindrical, and the first electrode may include a cylindrical electrode lacking a portion of its periphery. The dielectric wall structure may include at least one of quartz, aluminum oxide, and silicon nitride. The RF supply mechanism may include a mechanism for generating plasma by at least one of inductively coupled plasma, dielectric barrier discharge, and electron cyclotron resonance.

[0007] Another aspect of the present invention is a gas analyzer having the above-mentioned plasma generating device, a sampling unit that supplies a sample gas to be measured to the chamber, an analysis unit that analyzes the sample gas through the generated plasma, and a potential control unit that controls the floating potential of the plasma by a floating potential supply mechanism so that the plasma flows into the analysis unit. The analysis unit includes a filter unit that filters ionized gas in the plasma and a detector unit that detects the filtered ions, and the floating potential control unit may maintain the floating potential of the plasma positive with respect to the center potential of the filter unit so that the positively charged microplasma flows into the filter unit. An example of a gas analyzer is a mass spectrometer equipped with a quadrupole filter. It may include a unit that controls the floating potential of the plasma so that the inflow amount is variable depending on the analysis result or analysis conditions of the analysis unit. The main components may be analyzed at a high flow rate for a short time, or a high-precision analysis may be performed at a low flow rate for a long time. The sampling unit may supply only the sampling gas to the chamber, and generate the microplasma only by the sampling gas in the chamber without containing an assist gas such as argon that may cause noise.

[0008] Another aspect of the present invention is a process monitoring device having the above-mentioned gas analyzer. Also, another aspect of the present invention is a method for controlling a gas analyzer including a plasma generating device. This method includes controlling the floating potential of the plasma by a floating potential supply mechanism including a first electrode arranged along the inner surface of the chamber so that the plasma flows into the analysis unit. These methods may be provided as a program (program product) recorded on an appropriate recording medium. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing an overview of a gas analyzer including a plasma generating device. [Diagram 2] FIG. 1 is a diagram showing the configuration of a gas analyzer. [Diagram 3]1 is a free chart outlining the control of plasma floating potential in a gas analyzer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] 1 shows an example of a gas analyzer including a plasma generating device (plasma generating unit). This gas analyzer 1 functions as a process monitoring device (process monitor) 50 that monitors a process by analyzing a sample gas supplied from the process. The gas analyzer 1 includes a plasma generating unit 10 that generates plasma from a sample gas (sampling gas, gas sample) from the process, an analysis unit (analyzer) 21 that analyzes the sample gas via the generated plasma, a control unit (control device, control system) 51, and an exhaust system 60.

[0011] 2 shows in more detail the configuration of the gas analyzer 1 functioning as the process monitor 50. The gas analyzer 1 analyzes a sample gas 9 supplied from a process chamber 71 in which a plasma process is carried out. The plasma process carried out in the process chamber 71 is typically a process for producing various types of films or layers on a substrate or a process for etching a substrate, and includes CVD (Chemical Vapor Deposition) or PVD (Physical Vapor Deposition). The plasma process may also be a process for stacking various types of thin films on optical components such as lenses and filters as substrates.

[0012] The process monitor 50 includes a gas analyzer 1 that analyzes a gas (sample gas) 9 supplied from a process chamber 71. The gas analyzer 1 includes a plasma generation unit (plasma generation device) 10 that generates plasma 19 of the sample gas 9 to be measured that is supplied from the process, a sampling unit (sampling device) 90 that supplies the sample gas 9 to be measured to the plasma generation device 10, and an analysis unit 21 that analyzes the sample gas 9 via the generated plasma 19. The plasma generation device 10 includes a chamber (sampling chamber) 12 that has a dielectric wall structure 12a and into which only the sample gas 9 to be measured that is supplied via the sampling device 90 flows, a high-frequency supply mechanism (RF supply mechanism, RF supply device) 13 that generates plasma 19 in the decompressed sampling chamber 12 by a high-frequency electric field and / or magnetic field via the dielectric wall structure 12a, and a floating potential supply mechanism (floating potential control mechanism, floating potential supply device) 16 that controls the potential (floating potential) Vf of the plasma 19 by a control electrode 17 in the sampling chamber 12.

[0013] The gas analyzer 1 of this example is a mass spectrometry type, and the analysis unit (analyzer) 21 has a filter unit (filter, in this example, a quadrupole filter) 20 that filters the ionized sample gas (sample gas ions) 8 generated as plasma 19 in the plasma generation device 10 according to the mass-to-charge ratio, a focus electrode (ion attraction optical system) 25 that attracts a part of the plasma 19 as an ion flow 8, a detector unit (detector) 30 that detects the filtered ions, and a vacuum container (housing) 40 that houses the analysis unit 21. The gas analyzer 1 includes an exhaust system 60 that maintains the inside of the housing 40 under an appropriate negative pressure condition (vacuum condition). The exhaust system 60 of this example includes a turbomolecular pump (TMP) 61 and a Roots pump 62. The exhaust system 60 is a dual type that also controls the internal pressure of the sampling chamber 12 of the plasma generation device 10 using an intermediate negative pressure formed between the TMP 61 and the Roots pump 62.

[0014] Only the sample gas 9 from the process chamber 71 flows into the sampling chamber 12, which has been depressurized by the exhaust system 60, through the sampling device 90, and plasma 19 is formed inside the sampling chamber 12. The chamber 12 is designed for the purpose of generating microplasma, which is neither macroplasma nor nanoplasma, and is in an intermediate region. An example of the microplasma 19 is a plasma whose size extends to an area of ​​about several mm to about 100 μm. Furthermore, in order to generate plasma 19 of this size, in the plasma generation unit 10, the plasma 19 for analysis is generated only by the sample gas 9 without using an assist gas (support gas) such as argon gas. The wall 12a of the sampling chamber 12 is made of a dielectric material, and examples of such dielectric materials are quartz, aluminum oxide (Al2O3), silicon nitride (SiN3), and other dielectric materials that are highly durable against plasma.

[0015] The sampling chamber 12 is a small chamber suitable for generating the microplasma 19. For example, the overall length of the sampling chamber 12 may be 1-100 mm, and the diameter may be 1-100 mm. The overall length and the diameter may be 5 mm or more, 10 mm or more, 80 mm or less, 50 mm or less, or 30 mm or less. The capacity of the sampling chamber 12 is 1 mm. 3 It may be 10 or more. 5 mm 3 The volume of the sampling chamber 12 may be 10 mm 3 It may be more than 30 mm 3 It may be more than 100 mm 3 The capacity of the sampling chamber 12 may be 10 4 mm 3 It may be less than 10 3 mm 3 With a space of this size, the potential (electric field) within the space can be easily controlled by the electrodes 17 disposed within the chamber.

[0016] The plasma generating mechanism (RF supply mechanism) 13 of the plasma generating unit 10 generates plasma 19 by an electric field and / or a magnetic field through a dielectric wall structure 12a inside the sampling chamber 12 without using an electrode or a plasma torch. An example of the RF supply mechanism 13 is a mechanism that excites the plasma 19 with radio frequency (RF) power. Examples of the RF supply mechanism 13 include inductively coupled plasma (ICP), dielectric barrier discharge (DBD), and electron cyclotron resonance (ECR). The plasma generating mechanism 13 of these types includes a high frequency power supply 15 and an RF field forming unit 14. A typical RF field forming unit 14 includes a coil arranged along a representative direction of the sampling chamber 12, for example, along one end face or along the diameter direction if the sampling chamber 12 is cylindrical.

[0017] The internal pressure of the sampling chamber (container) 12 is controlled to an appropriate negative pressure using an exhaust system 60 shared with the gas analyzer 1, an independent exhaust system, or an exhaust system shared with the process device. The internal pressure of the sampling chamber 12 may be a pressure at which the microplasma 19 is easily generated, for example, in the range of 0.01-1 kPa. When the internal pressure of the process chamber 71 is controlled to about 1-several hundreds of Pa, the internal pressure of the sampling chamber 12 may be controlled to a lower pressure, for example, about 0.1-several tens of Pa, or may be controlled to 0.1 Pa or more, or 0.5 Pa or more, 10 Pa or less, or 5 Pa or less. For example, the inside of the sampling chamber 12 may be decompressed to about 1-10 mTorr (0.13-1.3 Pa). By maintaining the sampling chamber 12 at the above-mentioned reduced pressure, it is possible to generate the microplasma 19 at a low temperature using only the sample gas 9.

[0018] In the process monitor 50 (gas analyzer 1), the object to be monitored is the sample gas 9 supplied from the process chamber 71 in which the plasma process is carried out via the sampling device 90. In the sampling chamber 12, the plasma 19 can be maintained by supplying RF power under appropriate conditions without using arc discharge or a plasma torch, and by only introducing the sample gas 9. By eliminating the need for a support gas such as argon gas, the plasma 19 in which only the sample gas 9 is ionized can be generated and supplied to the gas analysis unit 21. This makes it possible to provide a gas analyzer 1 that has high measurement accuracy for the sample gas 9 and can quantitatively measure not only the gas components but also the components. Therefore, in the process monitor (process monitoring device) 50 equipped with the gas analyzer 1, the internal state of the process chamber 71 of the process device can be stably and accurately monitored for a long period of time.

[0019] Furthermore, in order to obtain measurement results in the gas analyzer 1 that allow for stable and accurate monitoring over a long period of time, it is also important to generate plasma 19 with a stable floating potential Vf or charging voltage in the sampling chamber 12. In this gas analyzer 1, controlling the floating potential of plasma 19 enables even more stable measurements.

[0020] In the process monitor 50, the plasma 19 of the sample gas 9 is generated by the sampling chamber 12 dedicated to gas analysis, which is independent of the process chamber 71. Therefore, the microplasma 19 suitable for sampling and gas analysis can be generated in the sampling chamber 12 under conditions different from those of the process chamber 71. For example, even when the process plasma or cleaning plasma is not generated in the process chamber 71, the internal state of the process chamber 71 can be monitored by turning the sample gas 9 into plasma. The sampling chamber 12 may be a small chamber (miniature chamber) suitable for generating the microplasma 19, for example, a few mm to a few tens of mm. The small capacity of the sampling chamber 12 allows the entire analyzer 1 to be compact and lightweight, and provides a gas analyzer 1 suitable for real-time measurement. The gas analyzer 1 may be portable or handy.

[0021] The floating potential supply mechanism (supply device, floating potential control mechanism) 16 that controls the potential (floating potential) of the plasma 19 includes a cylindrical control electrode 17 arranged along the inner surface of the sampling chamber 12, and a DC power supply 18 that controls the potential of the control electrode 17. The control electrode 17 may have a cylindrical shape with a portion of the circumferential surface missing, which can suppress the generation of eddy currents. If there is no problem with the corrosiveness of the sample gas 9, the control electrode 17 may be made of metals such as stainless steel, nickel, and molybdenum. If the corrosion resistance of the sample gas 9 is taken into consideration, a corrosion-resistant conductive material such as hastelloy, tungsten, titanium, and carbon (graphite) may be used.

[0022] The sampling chamber 12 may be cylindrical. In this plasma generation unit 10, the RF field forming unit 14 is arranged, for example, along one end face of the cylindrical sampling chamber 12 in a diameter direction (first direction) perpendicular to the central axis direction (second direction) crossing the chamber 12, and an electrode (first electrode) 17 for controlling the floating potential Vf is arranged along the cylindrical inner surface in the circumferential direction (second direction) of the chamber 12 along the central axis direction (second direction). With this configuration, an RF field for forming the plasma 19 is supplied by the RF field forming unit 14 arranged facing the opening at one or both ends of the cylindrical control electrode 17 for controlling the floating potential. Therefore, interference between the field for generating the plasma 19 and the field for controlling the floating potential of the plasma 19 can be suppressed, so that the plasma 19 can be stably generated and the floating potential can be easily controlled.

[0023] The electrode (first electrode) 17 for controlling the floating potential Vf may be cylindrical, may have a shape with a part of a cylinder missing, or may be a combination of a semi-cylindrical shape and a flat surface (plate). The RF field provided by the RF field providing unit 14 allows the microplasma 19 to be formed so as to float in the range surrounded by the first electrode 17, and the potential control of the microplasma 19 by the first electrode 17 becomes easy. In particular, when the size of the microplasma 19 (the size of the space in which the microplasma 19 is generated) is such that the electrode 17 and the RF field providing unit 14 are arranged so as to be perpendicular to each other, the plasma 19 can be generated inside the electrode 17 by providing an RF field from one or both ends of the electrode 17. The arrangement of the electrode 17 and the RF field providing unit 14 for controlling the floating potential Vf is not limited to the above, but arranging them so as to be perpendicular to each other is one of the arrangements suitable for suppressing mutual interference to efficiently generate the plasma 19 and controlling the floating potential (floating voltage) Vf of the generated plasma 19.

[0024] The control unit (control device) 51 of the analysis unit 21 may also serve as the control unit of the analysis device 1, which is the process monitoring device 50. The control device 51 includes a filter control unit (filter control function, filter control device) 53 that controls the filter unit (filter) 20, a detector control unit (detector control function, detector control device) 54 that controls the detector unit (detector) 30, and a management control device (management device, management function, management unit) 55. The control unit 51 may include computer resources including a memory 57 and a CPU 58, and the function of the control unit 51 may be provided by a program 59 recorded in the memory 57. The program (program product) 59 may be provided by being recorded on an appropriate recording medium.

[0025] The analysis unit 21 in this example is of a mass spectrometry type, particularly a quadrupole mass spectrometry type, and the filter unit 20 is a quadrupole filter. The filter control unit 53 includes a function as a driving unit (RF / DC unit) that applies high frequency and direct current to the quadrupole. The filter unit 20 filters the ionized sample gas (ion flow) 8 supplied as the microplasma 19 based on the mass-to-charge ratio. The detector control unit 54 includes a function of capturing the ion current generated by the ions that have passed through the filter unit 20 in a detector unit (detection unit, collector unit, detector) 30, for example, a Faraday cup, and detecting the components contained in the sample gas 9.

[0026] The management control device (management control unit) 55 controls the measurement (detection) mode executed by the analysis unit 21. The measurement modes include a mode for measuring the main components contained in the sample gas 9 in a short time, a mode for measuring all components contained in the sample gas 9 in a relatively long time, a mode for detecting one or more specific components of the sample gas 9, and a mode for detecting a component in a predetermined mode when a test gas with a known component is supplied as the sample gas, and changing the settings of the filter unit 20 and the detector unit 30 or calibrating the measurement result. The management control unit 55 may have a function for controlling the amount of plasma 19 flowing into the analysis unit 21 as the ion flow 8, or requesting a change in the floating potential Vf of the plasma 19 to be controlled, when the ratio of the component to be measured is too high or too low and the measurement result cannot be obtained within the range where the detector 30 can obtain an appropriate sensitivity.

[0027] The plasma generation control unit (plasma generation control device, generation control device) 11 that controls the plasma generation unit 10 may be a programmable control device, and includes a function (RF control unit) 11a that controls the frequency, voltage, etc. of the high frequency power supply 15 for generating plasma 19 in the sampling chamber 12, and a function (plasma potential control unit, potential control device, voltage control device) 11b that controls the voltage supplied to the control electrode 17 of the floating potential supply mechanism 16. The plasma generation control unit 11 may be provided with a function 11c that controls the internal pressure of the sampling chamber 12 by a pressure control valve 65 provided in the connection line with the exhaust system 60. By controlling these factors, the plasma 19 can be stably generated in the sampling chamber 12 even if the type of process performed in the process chamber 71 is changed or the state of the process is changed based on a request from the management unit 55 of the control device 51 of the analysis unit 21. Therefore, the sample gas 9 can be continuously analyzed by the process monitoring device 50 including the analysis device 1, and the process can be monitored.

[0028] The potential control unit 11b controls the floating potential Vf of the plasma 19 by the first electrode 17 arranged along the inner surface of the chamber 12 so that the plasma 19 flows from the chamber 12 to the analysis unit 21 as an ion flow 8. When detecting and measuring positive ions of the plasma 19 of the sample gas 9, a voltage is supplied to the control electrode 17 so that the plasma potential (floating potential) floats at about +5 to 15 V positive (positive potential) with respect to the central potential of the quadrupole electric field. By maintaining the floating potential Vf of the plasma 19 at a positive potential with respect to the central potential of the filter unit 20, the plasma 19, i.e., the positive ions to be detected, can be easily supplied to the filter unit 20, enabling highly accurate detection or measurement. The central potential of the quadrupole is applied with a potential of +10 V or more, for example, about +10 V to 100 V, when detecting positive ions, in order to reduce noise due to the detection of stray ions and stray electrons. When it is necessary to measure negative ions, the floating potential of the plasma 19 serving as the ion source may be negatively biased with respect to the ground potential, and the Faraday cup of the detector unit 30 may be set to the ground potential.

[0029] The potential control unit 11b includes a first control unit (control device) 11x that sets the floating potential Vf to maintain a reference potential V0 having a predetermined potential difference ΔV set in advance with respect to the center potential of the filter unit 20, and a second control unit (control device) 11y that varies the floating potential Vf up and down with respect to the reference potential V0 so that the amount of plasma 19 flowing into the analysis unit 21 changes depending on the analysis results or analysis conditions of the analysis unit 21. That is, the potential control unit 11b is configured to maintain the floating potential Vf at a reference potential V0 having a predetermined potential difference ΔV set in advance with respect to the center potential of the filter unit 20, and, upon request, vary the floating potential Vf up and down with respect to this reference potential V0 so that the amount of plasma 19 flowing into the analysis unit 21 changes depending on the analysis results or analysis conditions of the analysis unit 21.

[0030] For example, if a mode in which the main components contained in the sample gas 9 are measured by the analysis unit 21 in a short time is set in the management control unit 55, the potential control unit 11b can change the floating potential Vf with the second control function 11y in a direction that increases the potential difference with respect to the reference potential V0, thereby creating a large voltage gradient with the analysis unit 21 and increasing the amount of inflow of the plasma 19. Conversely, if a mode in which all components contained in the sample gas 9 are measured in a relatively long time is set in the management control unit 55, the potential control unit 11b can change the floating potential Vf with the second control function 11y in a direction that decreases the potential difference with respect to the reference potential V0, thereby reducing the voltage gradient with the analysis unit 21 and decreasing the amount of inflow of the plasma 19 into the analysis unit 21. When the ratio of the component to be measured is too high or too low and the measurement result is not within the range where the detector 30 has an appropriate sensitivity, the management control unit 55 may request the potential control unit 11b to set a floating potential Vf so that an appropriate voltage gradient is created between the plasma 19 in the chamber 12 and the analysis unit 21, and the potential control unit 11b may control the potential of the electrode 17 to set an appropriate floating potential Vf for the plasma 19.

[0031] FIG. 3 shows an outline of a method for controlling the floating potential Vf of the plasma generating device 10 of the analyzer 1 in the form of a flowchart. In step 81, if the potential control unit 11b does not receive a request to change the floating potential Vf, the potential control unit 11b sets the floating potential Vf to a preset reference potential V0 in step 82, for example, to any value in the range of about +5 to +15 V with respect to the central potential of the quadrupole electric field. If there is a request to change the floating potential Vf from the management control unit 55 of the analyzer 21, etc., the management control unit 55 responds to the request. For example, in step 83, if there is a request to increase the inflow amount of the microplasma 19 flowing in as the ion flow 8 to the filter 20 of the analysis unit (analyzer) 21, in step 84, the floating potential Vf is set (varied) in a direction in which the potential difference is expanded (increased, opened), for example, to a higher potential. In step 85, if there is a request to decrease (reduce) the inflow amount of the plasma 19, in step 86, the floating potential Vf is set (varied) in a direction in which the potential difference is reduced (reduced), for example, to a lower potential. If there is a request from the management control unit 55 for a change in mode, such as a short-term measurement or a precise measurement, rather than a request to indicate the inflow amount, then in step 87 a floating potential Vf appropriate for the given measurement mode is set.

[0032] This control method is just one example, and the plasma generating device 10 is equipped with a potential control mechanism (potential supply mechanism, potential supply device) 16 including an electrode 17 for controlling the floating potential arranged in the chamber 12, so that the potential of the microplasma 19 supplied from the chamber 12 can be freely adjusted depending on the requirements of the application using the plasma generating device 10.

[0033] In order to prevent detection of noise components due to excess stray electrons (negative charges), the filter unit (mass spectrometer) 20 and the detector unit (Faraday cup) 30 may be simply surrounded by a shield such as a pipe. In addition, although the above description is given taking a quadrupole type mass spectrometer as an example, the filter unit 20 may be of an ion trap type or of other types such as a Wien filter. In addition, the filter unit 20 is not limited to a mass spectrometer type, and may be one that filters gas molecules or atoms using other physical quantities such as ion mobility. In addition, the gas analysis unit may be an optical analysis device such as an emission analysis unit. Although an example of a plasma generation device used in a gas analysis device is shown, the application of microplasma is not limited to gas analysis, and a wide variety of applications such as inactivation of bacteria in microfabrication and health care are currently being considered, and the present invention is also effective in these applications.

[0034] Furthermore, while particular embodiments of the present invention have been described above, various other embodiments and modifications may be conceived 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]

[0035] 10 Plasma generating device 12 Chamber 13 RF supply mechanism 16 Floating potential supply mechanism 17 First electrode

Claims

1. A microplasma generating device, comprising: a chamber having a dielectric wall structure and into which a gas to be converted into plasma flows; an RF supply mechanism for generating a plasma within the chamber by electric and / or magnetic fields through the dielectric wall structure; a floating potential supply mechanism including a first electrode disposed along an inner surface of the chamber.

2. In claim 1, the RF supply mechanism includes an RF field unit disposed in a first direction relative to the chamber; The first electrode includes an electrode disposed in a second direction relative to the chamber.

3. In claim 1 or 2, the chamber is cylindrical; The plasma generating device, wherein the first electrode includes a cylindrical electrode having a portion of its circumferential surface missing.

4. In any one of claims 1 to 3, The plasma generating device, wherein the dielectric wall structure includes at least one of quartz, aluminum oxide, and silicon nitride.

5. In any one of claims 1 to 4, The plasma generating device, wherein the RF supply mechanism includes a mechanism for generating plasma by at least one of inductively coupled plasma, dielectric barrier discharge, and electron cyclotron resonance.

6. A plasma generating device according to any one of claims 1 to 5, A sampling unit for supplying a sample gas to be measured to the chamber; an analysis unit for analyzing the sample gas via the generated plasma; a potential control unit that controls the floating potential of the plasma by the floating potential supply mechanism so that the plasma flows into the analysis unit.

7. In claim 6, The potential control unit includes a unit for controlling a floating potential of the plasma so that an inflow amount is variable depending on an analysis result or an analysis condition of the analysis unit.

8. In claim 6 or 7, A gas analyzer, wherein the sampling unit supplies only the sampling gas to the chamber, and the plasma is generated in the chamber by only the sampling gas.

9. In any one of claims 6 to 8, The analysis unit includes a filter unit for filtering the ionized gas in the plasma; a detector unit for detecting the filtered ions; The potential control unit includes a unit that maintains a floating potential of the plasma at a positive potential with respect to a central potential of the filter unit.

10. A process monitoring device comprising a gas analyzer according to any one of claims 6 to 9.

11. A method for controlling a gas analyzer, comprising the steps of: The gas analyzer includes a microplasma generator into which a sample gas to be measured flows, and an analysis unit that analyzes the sample gas through the plasma generated by the generator, The generator includes a chamber having a dielectric wall structure into which the sample gas flows, an RF supply mechanism for generating plasma in the chamber by an electric field and / or a magnetic field through the dielectric wall structure, and a floating potential supply mechanism including a first electrode disposed along an inner surface of the chamber; The method includes controlling a floating potential of the plasma by the floating potential supply mechanism so that the plasma flows into the analysis unit.

12. In claim 11, The method, wherein the controlling includes controlling a floating potential of the plasma so as to vary an inflow amount according to an analysis result of the analysis unit.

13. In claim 11 or 12, the analysis unit includes a filter unit for filtering ionized gas in the plasma, and a detector unit for detecting the filtered ions; The method, wherein the controlling comprises maintaining a floating potential of the plasma positive with respect to a center potential of the filter unit.

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