Gas analyzer and control method

Abstract

To provide a device that can reduce noise in an analyzing device that ionizes sample gas to detect a component included in the sample gas.SOLUTION: A gas analyzing device 1 has: an ionization device 10 that generates an ion current 17 of sample gas 9; an analyzer 20 that analyzes the ion current supplied from the ionization device; a first ion path 41 that guides the ion current nonlinearly from the ionization device to an inlet of the analyzer; and a blocking device 29 that intermittently blocks and releases, by using an electric filed or a magnetic filed, the ion current on at least part of a path of the ion current reaching a mass filter 25 of the analyzer through the first ion path.SELECTED DRAWING: Figure 1

Description

Technical Field

[0004] , , , ,

[0005] , , , , , ,

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

Background Art

[0002] Patent Document 1 describes simplifying the configuration of an ion deflection lens of a plasma mass spectrometer and facilitating adjustment. Therefore, a cylindrical intermediate electrode with an obliquely cut end face is provided between a first electrode plate and a second electrode plate provided substantially perpendicular to the ion emission direction from the nozzle, and a DC voltage is applied to each electrode. Both electric fields are inclined, and ions are deflected by both electric fields. On the other hand, since plasma light travels straight, it is shielded by the second electrode plate.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0006] This gas analyzer can employ the following control method, enabling highly accurate measurements while suppressing the influence of light from the ionizer and other noise. This control method includes the following steps. 1. Obtain the first detection data using an analyzer while the passage of the ion flow is blocked by a blocking device. 2. Obtain the second detection data using an analyzer when the ion flow is not blocked by the blocking device, i.e., when the ion flow is open. 3. Output the detection result including the difference between the second detection data and the first detection data. The first and second detection data may include spectral data.

[0007] While light generated during ionization travels linearly, the first path guides the ion flow non-linearly (guiding it in a curved or bendy manner), thereby suppressing the influence of light that becomes noise in the analyzer and improving analytical accuracy. However, in the first path, it is impossible to completely block (shield) the light in order to guide the ion flow, and some of the light generated during ionization may reach the analyzer due to leakage or stray light, potentially becoming a source of noise that affects the measurement results. In this invention, instead of further improving the light shielding performance to reduce noise, or in conjunction with doing so, the background measurement result (first detection data) is obtained with the ion flow blocked (blocked), and the difference is obtained from the second detection data with the ion flow not actively blocked, thereby enabling the acquisition of highly accurate measurement results with further reduced noise components.

[0008] The gas analyzer has a control device for controlling the gas analyzer, and the control device may include a first function of acquiring first detection data by an analyzer when the passage of ion flow is blocked by a blocking device, a second function of acquiring second detection data by an analyzer when the passage of ion flow is opened by the blocking device, and a third function of outputting a detection result including the difference between the second detection data and the first detection data.

[0009] Typically, the control device is a device that executes a program, and the program to be controlled includes instructions to acquire first detection data by an analyzer with the passage of ion flow blocked by a blocking device, acquire second detection data by an analyzer with the passage of ion flow released by the blocking device, and output a detection result including the difference between the second detection data and the first detection data. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1(a) shows the front right, and Figure 1(b) shows the front left. [Figure 2]A perspective view showing the internal schematic configuration of a gas analyzer with its housing unfolded. [Figure 3] A block diagram showing the schematic configuration of a gas analyzer. [Figure 4] A diagram showing some examples of data obtained from a gas analyzer. [Figure 5] A flowchart illustrating the control method for a gas analyzer. [Figure 6] A diagram showing a schematic configuration of another example of a gas analyzer. [Modes for carrying out the invention]

[0011] Figures 1(a) and 1(b) show the external appearance of the gas analyzer viewed from the front right and front left. This gas analyzer 1 is a hybrid type equipped with a microplasma generator and an electron shock (EI) ion source as ionizers (ion sources). An example of the size and weight of gas analyzer 1 is 400 mm in length, 297 mm in width, 341 mm in height, and 15 kg in weight, and it operates on a 24 VDC (350 W) power supply. Gas analyzer 1 includes a sample inlet 3a for plasma generation and a sample inlet 3b for EI ionization, and includes several ports 4 on the side for data input and output.

[0012] Figure 2 shows the gas analyzer 1 with the upper housing 2a and side panel 2b removed. The gas analyzer 1 includes an ionization unit (ion generation unit) 10 that ionizes the sample gas (sampling gas, gas sample) supplied from the process to be monitored, an analysis unit (analyzer) 20 that analyzes the sample gas via the generated ions (ion flow), a control module 30 for the analysis unit 20, a system controller (programmable logic controller, PLC) 50 that controls the gas analyzer 1 and outputs measurement data, and an exhaust system 60.

[0013] Figure 3 shows a schematic configuration of a process monitor 100 as an example of a system including a gas analyzer 1. The gas analyzer 1 analyzes a sample gas 9 supplied from a process chamber 101 where the plasma process to be monitored is carried out. The plasma process carried out in the process chamber 101 is typically a process of creating various types of films or layers on a substrate, or a process of etching the substrate, and includes CVD (Chemical Vapor Deposition) or PVD (Physical Vapor Deposition). The plasma process may also be a process of stacking various types of thin films on an optical component such as a lens or filter as a substrate.

[0014] For example, in semiconductors, in recent years, semiconductor chip structures have become three-dimensional due to demands for increased memory capacity, improved logic speed, and lower power consumption. As a result, semiconductor process control has become more complex, requiring atomic-level quality and increasing measurement and monitoring costs. Monitoring gases containing reactants and by-products is crucial for process matching, transition point measurement during film deposition, and endpoint detection during etching. Currently, it is considered difficult to comprehensively monitor the process using plasma emission spectroscopy (OES), which is the standard method. On the other hand, residual gas analyzers and mass spectrometers using conventional thermal filaments as ion sources suffer from lifespan issues due to damage caused by semiconductor gases.

[0015] In the process monitoring system 100 using the gas analyzer 1 in this example, innovative process control can be provided by performing real-time monitoring even in harsh environments and providing highly reliable measurement results. The gas analyzer 1 functions as a total solution platform developed with the aim of dramatically improving throughput and maximizing yield in semiconductor chip manufacturing. As described above, the gas analyzer 1 in this example has a very small footprint and can be directly connected to the chamber 101 for on-site use. Furthermore, standard protocols currently mainly adopted in semiconductor manufacturing process equipment, such as the Either CAT protocol, can be installed on the PLC 50 and integrated into the process equipment control system 100.

[0016] The gas analyzer 1 includes an ionizer 10 that generates ions (ion stream) 17 of a sample gas 9, and an analyzer (analysis unit) 20 that analyzes the ions 17 supplied from the ionizer 10. The ionizer 10 includes a plasma generation unit (plasma generator) 11 that generates plasma (microplasma) 19 of the sample gas 9 to be measured, supplied from the process via a sample input 3a, and supplies it to the analysis unit 20 as an ion stream 17. The plasma generation unit 11 includes a chamber (sample chamber) 12 into which the sample gas 9 to be measured flows, which has a dielectric wall structure 12a, a high-frequency supply device (RF supply mechanism) 13 that generates plasma 19 in the depressurized sample chamber 12 by a high-frequency electric field and / or magnetic field via the dielectric wall structure 12a, and a plasma controller 16 that controls the frequency and power of the high frequency.

[0017] The gas analyzer 1 in this example is a mass spectrometry analyzer that can continuously or intermittently analyze the sample gas 9 supplied from the process 100 at short intervals. The analysis unit 20 includes a filter unit (mass filter, in this example, a quadrupole part) 25 that filters the flow (ion flow) 17 of the ionized sample gas (sample gas ions) by mass-to-charge ratio, and a detector unit 26 that detects the filtered ions. The gas analyzer 1 further includes a vacuum container (housing) 40 that houses the filter unit 25 and the detector unit 26, and an exhaust system 60 that maintains the inside of the housing 40 under appropriate negative pressure conditions (vacuum conditions). The exhaust system 60 in this example includes a turbomolecular pump (TMP) 61 and a Roots pump (suction stage, Drag stage) 62. The exhaust system 60 is of a split-flow type that also controls the internal pressure of the sample chamber 12 of the plasma generation device 11. Among the multi-stage TMPs 61 of the exhaust system 60, the stage that provides a negative pressure suitable for the internal pressure of the chamber 12, or the input of the Roots pump 62 communicates with the chamber 12 so that the internal pressure of the chamber 12 is controlled.

[0018] The mass filter 25 in this example includes four cylindrical or columnar electrodes (hyperquad, HyperQuad) 25a with the inner surfaces finished to be hyperboloids in order to form a hyperbolic electric field for filtering by mass-to-charge ratio. The quadrupole type mass filter 25 may be one in which a large number, for example, nine columnar electrodes are arranged to form a matrix (array) so as to form a plurality of pseudo-hyperbolic electric fields. The detector unit 26 includes a Faraday cup (FC, Faraday Cap) and a secondary electron multiplier (SEM, Secondary Electron Multiplier), and these can be used in combination or switched. The detector unit 26 may be of other types such as a channel type secondary electron multiplier (CEM, Channel Electron Multiplier), a microchannel plate (MP, Microchannel Plate).

[0019] The plasma generation unit 11 of this example includes a sample chamber 12 for plasma generation integrally incorporated inside a housing 40. The outer shell of the chamber 1二十的英文翻译-百度翻译2 is made of Hastelloy, and an insulated cylindrical electrode is inserted inside, where plasma 19 is generated. Only the sample gas 9 flows into the evacuated sample chamber 12 from the process chamber 101 to be monitored via the sample input 3a, and plasma (microplasma) 19 is formed inside the sample chamber 12. That is, in the plasma generation unit 11, the assist gas (support gas) such as argon gas is not used, and the plasma 19 for analysis is generated only by the sample gas 9. The wall 12a of the sample chamber 12 is composed of a dielectric member (dielectric), and an example thereof is a dielectric with high durability against plasma such as quartz, aluminum oxide (Al2O3), and silicon nitride (SiN3).

[0020] The plasma generation device (RF supply mechanism) 13 of the plasma generation unit 11 generates plasma 19 by an electric field and / or a magnetic field through the dielectric wall structure 12a without using a plasma torch inside the sample chamber 12. An example of the RF supply mechanism 13 is a mechanism that excites plasma 19 with high-frequency (RF, Radio Frequency) power. Examples of the RF supply mechanism 13 include methods such as inductively coupled plasma (ICP), dielectric barrier discharge (DBD), and electron cyclotron resonance (ECR). The RF supply device 13 that generates plasma by these methods may include a high-frequency power source and an RF field formation unit. A typical RF field formation unit includes a coil arranged along the sample chamber 12.

[0021] The plasma controller 16 of the plasma generation unit 11 in this example includes a matching control unit 16a that maintains the plasma by adjusting (matching) the frequency of the RF field supplied by the RF supply device 13, and a function (ignition unit) 16b that changes the RF frequency of the matched state to ignite the plasma. The ignition unit 16b can ignite the plasma using the RF supply device 13 by, for example, applying high-power high-frequency power at a frequency higher than the matching frequency in a pulsed manner for a short time, for example, about 10 ms. Therefore, the plasma can be easily ignited without providing electrodes for conventional glow discharge or mechanisms that provide high-voltage stimulation such as piezoelectric elements. After the plasma is ignited, the plasma can be generated and maintained by transitioning the RF supply device 13 to a steady-state operation. The plasma generation unit 11 may also be of a type that forms an inductively coupled plasma (ICP) with an assist gas such as argon gas and then introduces a sample gas for ionization.

[0022] The internal pressure of the sample chamber 12 in this example may be in the range of 0.01-1 kPa, which is a pressure at which plasma is easily generated. If the internal pressure of the process chamber 101 is controlled to about 1-several hundred Pa, the internal pressure of the sample chamber 12 may be controlled to a lower pressure, for example, about 0.1-several tens of Pa, and may be controlled to be 0.1 Pa or higher, or 0.5 Pa or higher, 10 Pa or lower, or 5 Pa or lower. For example, the inside of the sample chamber 12 may be reduced to about 1-10 mTorr (0.13-1.3 Pa). By maintaining the sample chamber 12 at the above-mentioned reduced pressure, it is possible to generate plasma 19 at a low temperature using only the sample gas 9. The sample chamber 12 may be a small chamber (miniature chamber) capable of generating microplasma 19, for example, a few millimeters to several tens of millimeters. By reducing the volume of the sample chamber 12, a gas analyzer 1 with excellent real-time capabilities can be provided. The sample chamber 12 may be cylindrical.

[0023] The gas analyzer 1 includes a first ion path 41 that nonlinearly guides the ion flow 17 from the outlet 18 of the plasma generator 11 of the ionizer 10, typically the chamber 12, to the inlet 27 of the analyzer (analysis unit) 20, and a second ion path 42 that guides the ion flow 17 from the inlet 27 of the analysis unit 20 to the filter unit 25 at a predetermined angle, typically parallel to the electrode 25a of the filter unit 25. The first ion path 41 includes a first electrostatic lens group 43 that extracts the ion flow 17 from the plasma 19 formed in the sample chamber (plasma chamber) 12 by the electric field through the chamber outlet 18 and guides the ion flow 17 to the inlet (opening) 27 which is located at a nonlinear position relative to the chamber outlet (chamber opening) 18. The inlet 27 of the analysis unit 20 is an opening provided in the barrier 27a, so that only the ion flow 17 that has passed through the inlet (opening) 27 is introduced into the analysis unit 20. In this example, the inlet 27 of the analysis unit 20 is positioned so as to be shifted (moved in a direction perpendicular to) the chamber outlet 18, either from the perspective of the second ion path 42 or with respect to the central axis of the quadrupole filter 25, that their respective openings do not overlap. The first ion path 41 is provided to guide the ion flow 17 between these openings 18 and 27 by bending it. Meanwhile, light leaking from the chamber outlet 18 is shielded from the analysis unit 20 by the barrier 27a.

[0024] The path of the ion flow 17 is bent under the influence of the electric field, while the light emitted from the excitation of the plasma 19 leaking from the chamber outlet 18 travels in a straight line unaffected by the electric field. Therefore, by providing an opening 27 that guides the ion flow 17 to the filter unit 25 at a position shifted relative to the chamber outlet 18, and providing a first ion path 41 between them that guides the ion flow 17 non-linearly (bent), it is possible to suppress the excitation light of the plasma emitted linearly from the chamber outlet 18 from reaching the inlet (opening) 27 of the analysis unit 20. As a result, it is possible to suppress the generation of secondary electrons that become background signals (noise) in the mass spectrum by the plasma excitation light reaching the detector 26, which in this example is a combination of a Faraday cup (FC) and a secondary electron multiplier (SEM).

[0025] The first ion path 41, which guides the ion flow 17 in a non-linear, bent (curved) manner, only needs to be able to block light traveling in a straight line, and may guide the ion flow 17 to bend once, or it may be bent further so that the chamber outlet 18 and the inlet 27 of the analysis unit 20 are aligned in a straight line. Furthermore, this first ion path 41 only needs to control the direction of the ion flow 17, and does not need to have the precision or aperture to control the direction of movement of individual ions, and may be a path designed so that such control or filtering is not performed.

[0026] The second ion path 42 includes a second electrostatic lens group 44 and an energy filter 28 positioned between them. The second electrostatic lens group 44 controls the direction of the ion flow 17 that flows into the second ion path 42 through the opening 27 of the barrier 27a provided between it and the first ion path 41. The energy filter 28 may be a Bessel-Box, a CMA (Cylindrical Mirror Analyzer), or a CHA (Concentric Hemispherical Analyzer). The Bessel-Box type energy filter 28 consists of a cylindrical electrode, a disc-shaped electrode (at the same potential as the cylindrical electrode) placed in the center of the cylindrical electrode, and electrodes placed at both ends of the cylindrical electrode. It operates as a bandpass filter that allows only ions with a specific kinetic energy to pass through due to the electric field created by the potential difference Vba between the cylindrical electrode and the end electrodes and the potential Vbe of the cylindrical electrode. Furthermore, the disc-shaped electrode positioned at the center of the cylindrical electrode prevents soft X-rays generated during plasma generation and light generated during gas ionization from directly entering the ion detector (detector) 26, thereby reducing noise. In addition, the energy filter 28 can also exclude ions and neutral particles generated in the ion generation section or externally that are incident on the filter unit 25 parallel to the central axis, thus suppressing their detection.

[0027] Furthermore, the energy filter 28 can, by controlling the electric field, block the passage of all ions (ionic streams) 17 with kinetic energy that are destined to pass through the second ion path 42 and be input to the filter unit 25. Therefore, the energy filter 28 functions as a blocking device 29 that intermittently blocks and releases the ionic streams 17 in at least a portion of the path of the ionic streams 17 that reach the mass filter 25 of the analyzer 20 via the first ion path 41, using an electric or magnetic field. Alternatively, or in cooperation with the energy filter 28, the electric field (potential) of some or all of the second electrostatic lens group 44 that controls the direction of the ionic streams 17 in the second ion path 42 may be controlled and used as a blocking potential, thereby functioning as a blocking device (blocking potential generator) 29 that intermittently blocks and releases the ionic streams 17 that reach the mass filter 25.

[0028] The ionizer 10 of the gas analyzer 1 in this example further includes a filament (EI ion source) 15 that ionizes the sample gas 9 to be measured, supplied from the process via the sample input 3b, by electron shock. The EI ion source 15 operates under high vacuum and can be used to operate the gas analyzer 1 at its ultimate pressure and for sensitivity correction when the process in the process chamber 101 under monitoring is under high vacuum conditions and it is difficult to generate microplasma 19. The supply of sample gas 9 to the sample input 3a for plasma ionization and the sample input 3b for EI ionization can be automatically switched by the process controller 105 using valves 103a and 103b located upstream.

[0029] In one embodiment, when the internal pressure of the process chamber 101 is high, for example 1 Pa or more, and it is a reactive process, the process controller 105 opens valve 103a to supply sample gas 9 to the gas analyzer 1. Furthermore, the control device (PLC module) 50 of the gas analyzer 1 generates plasma 19 of the sample gas 9 to extract an ion flow 17 and perform mass spectrometry. At this time, the EI ion source (filament) 15 is not lit, and valve (port) 103b is closed. When measuring at a low internal pressure of the process chamber 101, for example, the ultimate pressure, the process controller 105 closes the plasma-side port (valve) 103a, opens the EI-side port 103b to supply sample gas 9, and the control device 50 lights the filament (activates EI) to generate an ion flow 17 and perform mass spectrometry.

[0030] The gas analyzer 1 includes a control device (unit controller, module controller, control box, control module) 30 that controls each module of the analysis unit 20 under a system controller (system control device, PCL module) 50. The unit controller 30 includes a first lens control device (control unit, control function, circuit, module) 31 that controls the potential of the first electrostatic lens group 43, a second lens control device (control unit) 32 that controls the potential of the second electrostatic lens group 44, an energy filter control device (energy filter control unit) 33 that controls the potential of the energy filter 28, a filament control device (filament control unit) 34 that controls the filament current and voltage, a filter control device (quadrupole filter control unit) 35 that controls the RF and DC voltage of the mass filter 25, and a detector control device (detector control unit) 36 that controls the detector 26 to obtain the detected current. In this example, for instance, the control conditions for the first electrostatic lens 43 and the second electrostatic lens 44 are set to be the same as those for obtaining the mass spectrum using the analysis unit 20, allowing the ion flow 17 to pass through. By changing only the conditions for the energy filter 28, the ion flow 17 flowing into the mass filter 25 of the analysis unit 20 can be blocked or released.

[0031] The system control device (PLC module) 50 that controls the gas analyzer 1 includes computer resources such as a CPU and memory 59, and controls the gas analyzer 1 by downloading and executing a program (control program) 55. The program 55 includes instructions to make the PLC module 50 function as a first module (first function) 51 that performs a process (first process) to acquire first detection data 71 by the analysis unit (analyzer) 20 when the passage of ion flow 17 is blocked by the blocking device 29, a second module (second function) 52 that performs a process (second process) to acquire second detection data 72 by the analysis unit 20 when the passage of ion flow 17 is not blocked by the blocking device 29 (when the passage of ion flow 17 is released), and a third module (third function) 53 that performs a process (third process) to output a detection result 73 including the difference between the second detection data 71 and the first detection data 72.

[0032] Figure 4 schematically shows several examples of mass spectra (spectral data, spectra). Figure 4(a) is an example of detection results obtained by a conventional mass spectrometer that does not have a first ion path that bends and guides the ion flow 17, rather than the gas analyzer 1 in this example. That is, it is an example of a mass spectrum 79 obtained by inputting the ion flow 17 into the analysis unit 20 without shielding the emission of the plasma 19. The peak width P1 of the mass spectrum 79 is wide and the offset amount P2 is large, indicating that noise due to the emission of the plasma 19 reaching the detector 26 is reducing the accuracy of the detected mass spectrum.

[0033] Figure 4(b) shows an example of a mass spectrum obtained as a detection result in the gas analyzer 1 of this example. This mass spectrum 78 schematically shows the data (second measurement data) 72 measured when the passage of the ion flow 17 is not blocked by the blocking device 29 (open state). By guiding the ion flow 17 nonlinearly in the first ion path 41 by the analysis unit 20, it is possible to suppress the effect of emission from the linearly traveling plasma 19. As a result, the peak of the mass spectrum 78 becomes sharper (narrower), and the offset (noise floor) amount P2 is reduced. Furthermore, in this gas analyzer 1, it is possible to select the energy of the ions 17 input to the mass filter 25 by the energy filter 28. As a result, a mass spectrum with a sharper peak can be obtained.

[0034] Figure 4(c) shows the spectrum 77 obtained as a detection result in the gas analyzer 1 of this example, but schematically represents the data (first detection data) 71 measured by the analysis unit 20 with the passage of the ion stream 17 blocked by the blocking device 29. That is, spectrum 77 is an example of a detection spectrum obtained by the detector 26 with the conditions of the energy filter 28 set so that ions of all energies do not pass through, and the blocking device 29 is functioning. In the first ion path 41, the ion stream 17 is guided nonlinearly toward the aperture 27. However, in order to supply the analysis unit 20 with a sufficient amount of ion stream 17 containing ions of various mass-to-charge ratios (m / z) to be detected for measurement, it may not be possible to select the deflection angle of the ion stream 17 and / or the area of ​​the aperture 27 while prioritizing light shielding. In particular, when trying to realize a portable and compact gas analyzer 1, the length and angle of the ion stream 17 may not be sufficiently secured due to light shielding.

[0035] Furthermore, stray light almost always occurs inside the gas analyzer 1, and ions that are not filtered by the mass filter 25 may reach the detector 26. Therefore, inherent noise in the gas analyzer 1 is always possible, and it is difficult to block all such noise with hardware. In the gas analyzer 1, the first module (function) 51 of the PLC 50 blocks the ion flow 17 that is input to the mass filter 25 as designed by the blocking device 29, and measurements are performed. The data obtained in this process (first detection data) 71 can be used as noise (offset) inherent to the measurement conditions in the gas analyzer 1.

[0036] Figure 4(d) shows the mass spectrum 76 of the difference between the second detection data 72 (Figure 4(b)) measured by the third module (function) 53 of the PLC 50 when the ion flow 17 was not blocked by the blocking device 29 by the second module 52, and the first detection data 71 (Figure 4(c)) obtained by the first module 51 when the ion flow 17 was blocked by the blocking device 29. By subtracting the intrinsic noise spectrum (background spectrum) 77 of the analyzer 1 obtained as the first detection data 71 from the mass spectrum 78 obtained as the second detection data 72, a highly accurate mass spectrum 76 with almost no influence from noise including offset can be obtained and output as the detection result 73.

[0037] Figure 5 shows an overview of the control method for outputting measurement results with offset (noise) canceled in the gas analyzer 1. In step 81, the first module 51 determines whether or not to acquire the first detection data 71 related to the offset (noise). The gas analyzer 1 can basically generate an ion flow 17 continuously and can analyze the ion flow 17 continuously or intermittently to average it through short-term repetition. Therefore, under almost the same conditions, measurements can be repeatedly performed with the ion flow 17 blocked (stopped) and with the ion flow 17 open (not blocked). The first detection data 71 related to the offset may be acquired each time the second detection data 72 related to the mass spectrum is acquired, prioritizing accuracy, or it may be acquired periodically when a predetermined number of measurements or time has elapsed, prioritizing the time required for measurement, or at limited timings such as when the measurement conditions change or when the gas analyzer 1 is started.

[0038] To obtain the first detection data 71, in step 82, the energy filter 28 is set to function as a blocking device 29, and in step 83, the first detection data 71 is obtained by the analysis unit (analyzer) 20 with the energy filter 28 blocking the passage of ions 17. To obtain the second detection data 72, which includes the offset, rather than the first detection data 71 regarding the offset (noise), the second module 52 is used in step 84 to set the energy filter 28 to perform energy sorting of the ion flow 17 under predetermined conditions, and in step 85, the analysis unit 20 obtains the second detection data 72 regarding the mass spectrum with the ion flow 17 not blocked. Furthermore, in step 86, the third module 53 outputs the mass spectrum obtained by subtracting the first detection data 71 regarding the offset from the second detection data 72 obtained including the offset as the detection result 73.

[0039] In this analyzer 1, the first ion path 41, which bends and guides the ion flow 17, suppresses the effect of emission from the plasma 19, resulting in a sharp peak in the mass spectrum 78 included in the second detection data 72, with a small offset. Therefore, by almost simply subtracting the limited background information included in the first detection data 71 obtained by blocking the ion flow 17, a sharper mass spectrum with a smaller offset can be obtained without complex processing.

[0040] Figure 6 shows several different examples of the gas analyzer 1. The gas analyzer 1 shown in Figure 6(a) is an example in which the path of the ion flow 17 (first ion path) 41 is configured using an ion guide device (guide unit) 45 that controls the path instead of an electrostatic lens group. This guide unit 45 includes, for example, a cylindrical electrode 47 that surrounds the ion path 41, and deflection electrodes 46a and 46b placed inside it. When the ions to be guided are positively charged, the cylindrical peripheral electrode 47 is maintained at a positive potential, for example, about 100V, and the deflection electrodes 46a and 46b are maintained at ground potential, for example, 0V. The direction of the ion flow 17 is controlled along the electric field formed by these electrodes, and in the diagram, it is shifted up and down and bent twice nonlinearly before being guided to the opening 27 of the analysis unit 20. Therefore, the ion flow 17 from the chamber outlet 18 of the plasma generator 11, which is the ionization device 10, is guided nonlinearly to the opening 27 at the inlet of the analysis unit 20, thereby suppressing the influence of linearly traveling plasma light.

[0041] The gas analyzer 1 shown in Figure 6(b) is a device that has an energy filter 28 positioned in the ion path 41, which is configured to form an electric field that guides the ion flow 17 nonlinearly from the chamber outlet 18 of the plasma generator 11, which is the ionizer 10, and to function as a blocking device 29 that blocks the ion flow 17. As described above, the vessel box type energy filter 28 consists of a cylindrical electrode, a disc-shaped electrode positioned in the center of the cylindrical electrode, and electrodes positioned at both ends of the cylindrical electrode, and the ion flow 17 is guided nonlinearly so as to avoid the disc-shaped electrode positioned in the center of the cylindrical electrode. Typically, the ion flow 17 passes through the energy filter 28 in a curved channel that bypasses the disc-shaped electrode from the inlet to the outlet of the energy filter 28. Therefore, the disc-shaped electrode positioned in the center of the cylindrical electrode prevents soft X-rays generated during plasma generation and light generated during gas ionization from directly entering the detector 26. Therefore, even in gas analyzers 1 with these configurations, the influence of light generated in the plasma generator 11 can be suppressed by guiding the ion flow 17 nonlinearly. Furthermore, by measuring the offset (noise) while the ion flow 17 is blocked, it becomes possible to efficiently remove any remaining noise components, and a more accurate mass spectrum can be output as the detection result.

[0042] Although the above describes an example in which a quadrupole type is used as the mass filter 25 of the gas analysis unit 20, the mass filter 25 may be of other types, such as an ion trap or a Wien filter. The above discloses a control method for a gas analyzer. The gas analyzer includes an ionizer that generates an ion flow of a sample gas, an analyzer that continuously or intermittently analyzes the ion flow supplied from the ionizer, a first ion path that guides the ion flow nonlinearly from the ionizer to the inlet of the analyzer, and a blocking device that intermittently blocks and releases the ion flow in at least a portion of the path of the ion flow to the mass filter of the analyzer via the first ion path using an electric or magnetic field. The method includes acquiring first detection data by the analyzer while the passage of the ion flow is blocked by the blocking device, acquiring second detection data by the analyzer while the passage of the ion flow is released by the blocking device, and outputting a detection result including the difference between the second detection data and the first detection data. The first and second detection data may include spectral data. Disclosed above is a gas analyzer comprising: an ionizer that generates an ion flow of a sample gas; an analyzer that continuously or intermittently analyzes the ion flow supplied from the ionizer; a first ion path that nonlinearly guides the ion flow from the ionizer to the inlet of the analyzer; and a blocking device that intermittently blocks and releases the ion flow by an electric or magnetic field in at least a portion of the path of the ion flow to the mass filter of the analyzer via the first ion path. The ionizer may also include a device that plasma ionizes the sample gas. The ionizer includes a sample chamber with a dielectric wall structure and a reduced pressure, into which the sample gas flows from a process under monitoring; a high-frequency supply device that generates plasma in the sample chamber by at least one of an electric field and a magnetic field via the dielectric wall structure; and a plasma controller that controls the frequency and power of the high-frequency supplied from the high-frequency supply device, wherein the first ion path may include a path connecting the outlet of the sample chamber to the inlet of the analyzer. The plasma controller may include a function to ignite the plasma in the sample chamber by changing the frequency of the high-frequency supplied by the high-frequency supply device. The blocking device may include either a blocking potential generator or an energy filter. The gas analyzer includes a control device for controlling the gas analyzer, which may include a first function of acquiring first detection data by the analyzer when the passage of the ion flow is blocked by the blocking device, a second function of acquiring second detection data by the analyzer when the passage of the ion flow is opened by the blocking device, and a third function of outputting a detection result including the difference between the second detection data and the first detection data.In a system having a control device that executes a program for controlling the gas analyzer, the control program may include instructions to acquire first detection data by the analyzer when the passage of the ion flow is blocked by the blocking device, to acquire second detection data by the analyzer when the passage of the ions is released by the blocking device, and to output a detection result including the difference between the second detection data and the first detection data. The program for controlling the gas analyzer may have instructions to acquire first detection data by the analyzer when the passage of the ion flow is blocked by the blocking device, to acquire second detection data by the analyzer when the passage of the ions is released by the blocking device, and to output a detection result including the difference between the second detection data and the first detection data.

[0043] Furthermore, although specific embodiments of the present invention have been described above, various other embodiments and variations can be conceived by those skilled in the art without departing from the scope and spirit of the invention, and such other embodiments and variations are subject to the following claims, and the present invention is defined by the following claims. [Explanation of symbols]

[0044] 1 gas analyzer, 9 sample gases, 10 ionizers 29 Blocking device, 41 First ion pathway

Claims

1. An ionization apparatus for generating an ion flow of a sample gas, comprising a plasma generator for plasma ionizing the sample gas and an ion source for ionizing the sample gas by electron shock, An analyzer for analyzing the ion flow supplied from the ionizer, A first sample input that guides the sample gas to the plasma generator, A second sample input that guides the sample gas to the ion source, A first valve for opening and closing the first sample input, A second valve for opening and closing the second sample input, The system includes a control device that controls the first valve and the second valve to switch the input of the sample gas, The control device has a function of opening the first valve and closing the second valve when the internal pressure of the process chamber to which the sample gas is supplied is high, and inputting the sample gas into the plasma generator to plasma ionize it. A gas analyzer comprising a function that, when the internal pressure of the process chamber is low, closes the first valve and opens the second valve to supply the sample gas to the ion source and activate the ion source.

2. In claim 1, It also has a split-flow type exhaust system, A gas analyzer in which the first stage of the exhaust system is connected to the sample chamber of the plasma generator, and the second stage of the exhaust system is connected to the discharge side of the analyzer.

3. process chamber and An ionization apparatus for generating an ion flow of a sample gas from the process chamber, comprising a plasma generator for plasma ionization of the sample gas and an ion source for ionization of the sample gas by electron shock, An analyzer for analyzing the ion flow supplied from the ionizer, A first sample input that guides the sample gas to the plasma generator, A second sample input that guides the sample gas to the ion source, The system includes a control device that controls a first valve for opening and closing the first sample input and a second valve for opening and closing the second sample input to switch the input of the sample gas, The control device has a function of opening the first valve and closing the second valve when the internal pressure of the process chamber is high, and inputting the sample gas into the plasma generator to plasma ionize it. A system comprising a function that, when the internal pressure of the process chamber is low, closes the first valve and opens the second valve to supply the sample gas to the ion source and activate the ion source.

4. In claim 3, It also has a split-flow type exhaust system, A system in which the first stage of the exhaust system is connected to the sample chamber of the plasma generator, and the second stage of the exhaust system is connected to the discharge side of the analyzer.

5. process chamber and An ionization apparatus for generating an ion flow of a sample gas from the process chamber, comprising a plasma generator for plasma ionization of the sample gas and an ion source for ionization of the sample gas by electron shock, An analyzer for analyzing the ion flow supplied from the ionizer, A first sample input that guides the sample gas to the plasma generator, A second sample input that guides the sample gas to the ion source, A control method for a system having a control device that controls a first valve for opening and closing a first sample input and a second valve for opening and closing a second sample input to switch the input of the sample gas, The control device, when the internal pressure of the process chamber is high, opens the first valve and closes the second valve, inputting the sample gas into the plasma generator to ionize it into plasma. A control method comprising: closing the first valve and opening the second valve when the internal pressure of the process chamber is low, supplying the sample gas to the ion source, and activating the ion source.

Images