TW202401160A - Residual gas analyser - Google Patents

Abstract

Disclosed herein is a residual gas analyser, RGA, for determining the amounts of gas components in a vacuum tool, the RGA comprising a first detector and a second detector, wherein:the first detector is configured so that the largest gas component amount that is determinable by the first detector is greater than the largest gas component amount that is determinable by the second detector; the first detector is configured so that the smallest gas component amount that is determinable by the first detector is less than or equal to the largest gas component amount that is determinable by the second detector; and the second detector is configured so that the smallest gas component amount that is determinable by the second detector is less than the smallest gas component amount that is determinable by the first detector.

Description

residual gas analyzer

The present invention relates to residual gas analyzers for use with vacuum tools. More specifically, the techniques disclosed herein relate to operating residual gas analyzers in new ways such that they effectively have a greater dynamic range than is achievable by known techniques.

A lithography apparatus is a machine that applies a desired pattern to a substrate, usually to a target portion of the substrate. Lithography equipment may be used, for example, in the manufacture of integrated circuits (ICs). In IC manufacturing, patterning devices, which are alternatively referred to as masks or reticles, may be used to create circuit patterns to be formed on individual layers of the IC. This pattern can be transferred to a target portion (eg, a portion containing one or several dies) on a substrate (eg, a silicon wafer). Transfer of the pattern is typically performed by imaging onto a layer of radiation-sensitive material (resist) provided on the substrate. Typically, a single substrate will contain a network of adjacent target portions that are patterned sequentially. Known lithography apparatuses include: so-called steppers, in which each target portion is irradiated by exposing the entire pattern to the target portion at once; and so-called scanners, in which each target portion is irradiated by exposing the entire pattern to it in a given direction (the "scanning" direction). Each target portion is irradiated by scanning the pattern through the radiation beam while simultaneously scanning the substrate parallel or anti-parallel to this direction.

A theoretical estimate of the pattern printing limit can be given by Rayleigh's resolution criterion, as shown in equation (1): where λ is the wavelength of the radiation used, NA is the numerical aperture of the projection system used to print the pattern, k ₁ is the process-dependent adjustment factor (which is also called the Rayleigh constant), and CD is the feature size of the printed feature ( or critical size). From equation (1) it can be seen that a reduction in the minimum printable size of a feature can be obtained in three ways: by shortening the exposure wavelength λ, by increasing the numerical aperture NA, or by reducing the value of k ₁ .

In order to shorten the exposure wavelength and therefore the minimum printable size, the use of extreme ultraviolet (EUV) radiation sources has been proposed. EUV radiation is electromagnetic radiation having a wavelength in the range of 4 nm to 20 nm (eg, in the range 13 nm to 14 nm, eg, in the range 4 nm to 10 nm, such as 6.7 nm or 6.8 nm) . Possible sources include, for example, laser-generated plasma sources, discharge plasma sources, or sources based on synchrotron radiation provided by an electron storage ring.

Plasma can be used to generate EUV radiation. Radiation systems for generating EUV radiation may include lasers for exciting fuel to provide plasma, and source collector modules for containing the plasma. The plasma can be generated, for example, by directing a laser beam at a fuel, such as droplets of a suitable material (eg, tin), or a stream of a suitable gas or vapor (such as Xe gas or Li vapor). The resulting plasma emits output radiation, such as EUV radiation, which is collected using a radiation collector. The radiation collector may be a mirrored normal incidence radiation collector that receives radiation and focuses the radiation into a beam. The source collector module may include an enclosure or chamber configured to provide a vacuum environment to support the plasma. This radiation system is often referred to as a laser produced plasma (LPP) source.

In EUV vacuum tools, such as EUV lithography equipment and/or EUV sources, extremely high levels of cleanliness need to be maintained. Specifically, any contaminant gases within the EUV vacuum tool can damage the optical components within the EUV vacuum tool. The allowable levels of contaminant gases in EUV vacuum tools are lower than in most other vacuum tool applications.

There is often a need for improved identification and monitoring of contaminant gases within vacuum tools, such as EUV vacuum tools.

According to a first aspect of the present invention, a residual gas analyzer RGA for determining the amount of gas components in a vacuum tool is provided. The RGA includes a first detector and a second detector, wherein : The first detector is configured such that the maximum gas component amount that can be determined by the first detector is greater than the maximum gas component amount that can be determined by the second detector; the first detector is configured to Such that the minimum gas component amount that can be determined by the first detector is less than or equal to the maximum gas component amount that can be determined by the second detector; and the second detector is configured such that it can be detected by the second detector. The minimum gas component amount determined by the detector is less than the minimum gas component amount that can be determined by the first detector.

According to a second aspect of the present invention, a residual gas analyzer RGA for determining the pressure of gas components in a vacuum tool is provided. The RGA system includes: an RGA according to the first aspect; and a computer system; wherein: the computer system is configured to receive first and second current measurements from the first detector of the RGA, wherein the first current measurement is a determined quantity of one of the major gas components and the second The current measurement is a determined quantity of a primary gas component; the computer system is configured to receive a third current measurement from the second detector of the RGA, wherein the third current measurement is the secondary a determined quantity of a gas component; the computer system is configured to receive a pressure measurement that is substantially the pressure of the primary gas component; the computer system is configured to depend on the received pressure measurement and the receiving first current measurements and determining a pressure corresponding to the current measurements received from the first detector such that the pressure of the second gas component is determined; and the computer system is configured to A pressure corresponding to the current measurement received from the second detector is determined depending on the determined pressure of the second gas component and the received third current measurement.

According to a third aspect of the present invention, a method for determining gas composition by a residual gas analyzer RGA in a vacuum tool is provided, the method comprising: operating a first detector such that the first detector can The maximum gas component amount determined by the second detector is greater than the maximum gas component amount that can be determined by the second detector; the first detector is operated so that the minimum gas component amount that can be determined by the first detector is less than or equal to the minimum gas component amount that can be determined by the second detector. The maximum gas component amount determined by two detectors; and operating the second detector such that the minimum gas component amount that can be determined by the second detector is less than the minimum gas component amount that can be determined by the first detector .

According to a fourth aspect of the present invention, a computer-implemented method for measuring and determining pressure from a residual gas analyzer RGA is provided. The method includes: receiving first and second current measurements from a first detector of the RGA, wherein the first current measurement is a determined quantity of a primary gas component and the second current measurement is a determined quantity of a primary gas component; receiving a third current quantity from the second detector of the RGA measurement, wherein the third current measurement is a determined amount of the secondary gas component; receiving a pressure measurement that is substantially the pressure of the primary gas component; depending on the received pressure measurement and the receiving the first current measurements and determining the pressure corresponding to the current measurements by the first detector, so that the pressure of the second gas component is determined; and depending on the experience of the second gas component The pressure and the received third current measurement are determined and the pressure corresponding to the current measurement is determined by the second detector.

According to a fifth aspect of the present invention, a charged particle device is provided, which includes a residual gas analyzer RGA according to the first aspect, or an RGA system according to the second aspect.

Other features and advantages of the invention, as well as the structure and operation of various embodiments of the invention, are described in detail below with reference to the accompanying drawings. It should be noted that this invention is not limited to the specific embodiments described herein. Such embodiments are presented herein for illustrative purposes only. Additional embodiments will be apparent to those skilled in the relevant art based on the teachings contained herein.

Cross-references to related applications

This application claims priority to European Patent Application 22160788.0, filed on March 8, 2022 and the entire text of which is incorporated herein by reference.

This specification discloses one or more embodiments that feature the invention. The disclosed embodiments merely illustrate the invention. The scope of the invention is not limited to the disclosed embodiments. The present invention is defined by the patent claims appended hereto.

The described embodiments, and references in this specification to "one embodiment," "an embodiment," "an example embodiment," etc., indicate that the described embodiment may include a particular feature, structure, or characteristic, but each Embodiments may not necessarily include specific features, structures, or characteristics. Furthermore, these phrases are not necessarily referring to the same embodiment. In addition, when a specific feature, structure or characteristic is described in conjunction with an embodiment, it should be understood that it is within the scope of those skilled in the art to implement the feature, structure or characteristic in conjunction with other embodiments, whether explicitly described or not.

Embodiments of the present invention may be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the invention may also be implemented as instructions stored on machine-readable media, which may be read and executed by one or more processors. Machine-readable media may include any mechanism for storing or transmitting information in a form readable by a machine (eg, a computing device). For example, machine-readable media may include: read-only memory (ROM); random access memory (RAM); disk storage media; optical storage media; flash memory devices; electrical, optical, acoustic or other forms Propagated signals (such as carrier waves, infrared signals, digital signals, etc.); and others. In addition, firmware, software, routines, and instructions may be described herein as performing certain actions. However, it should be understood that these descriptions are for convenience only and that such actions are actually caused by a computing device, processor, controller or other device executing firmware, software, routines, instructions, etc.

However, before such embodiments are described in greater detail, it is instructive to present an example environment in which embodiments of the invention may be implemented.

Figure 1 schematically shows a lithography apparatus LAP including a source collector module SO. The apparatus includes: an illumination system (illuminator) IL configured to modulate a radiation beam B (e.g., EUV radiation); a support structure (e.g., a masking table) MT constructed to support a patterning device (e.g., a masking table) mask or patterning device) MA and connected to a first positioner PM configured to accurately position the patterning device; a substrate stage (e.g., wafer table) WT configured to hold a substrate (e.g., resist coated wafer) W and connected to a second positioner PW configured to accurately position the substrate; and a projection system (e.g., reflective projection system) PS configured to impart radiation from the patterning device MA The pattern of beam PB is projected onto a target portion C of substrate W (eg, containing one or more dies).

Illumination optical systems may include various types of optical components for directing, shaping, or controlling radiation, such as refractive, reflective, magnetic, electromagnetic, electrostatic, or other types of optical components, or any combination thereof.

The support structure MT includes a structure for receiving and holding the patterning device MA in a manner that depends on the orientation of the patterning device, the design of the lithography equipment, and other conditions such as, for example, whether the patterning device is held in a vacuum environment. part. The support structure may use mechanical, vacuum, electrostatic or other clamping techniques to hold the patterned device. The support structure may be, for example, a frame or a table, which may be fixed or moveable as required. The support structure ensures that the patterning device, for example, is in a desired position relative to the projection system.

The term "patterning device" should be interpreted broadly to mean any device that can be used to impart a pattern to a radiation beam in its cross-section so as to produce a pattern in a target portion of a substrate. The pattern imparted to the radiation beam may correspond to specific functional layers in the device produced in the target portion, such as an integrated circuit.

The patterning device may be transmissive or reflective. Examples of patterning devices include masks, programmable mirror arrays, and programmable LCD panels. Masking is well known in lithography and includes mask types such as binary, alternating phase shift, and attenuated phase shift, as well as various hybrid mask types. One example of a programmable mirror array uses a matrix arrangement of small mirrors, each of which can be individually tilted to reflect an incident radiation beam in different directions. The tilted mirrors impart a pattern in the radiation beam reflected by the mirror matrix.

Similar to illumination systems, projection systems may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic, or other types of optical components, suitable for the exposure radiation used or for other factors such as use of a vacuum. or any combination thereof. A vacuum may be required for EUV radiation because other gases may absorb too much radiation. Therefore, a vacuum environment can be provided to the entire beam path by virtue of the vacuum container and the vacuum pump.

As depicted here, the device is a reflective device (ie, a reflective device using reflective masks and reflective optics in the illuminator IL and projection system PS).

Lithography equipment may be of the type having two (dual stages) or more than two substrate stages (and/or two or more mask stages). In these "multi-stage" machines, additional stages can be used in parallel, or preparatory steps can be performed on one or more stages while one or more other stages are used for exposure.

Referring to Figure 1 , the illuminator IL receives a beam of EUV radiation from an EUV source SO. Methods for generating EUV radiation include, but are not necessarily limited to, converting a material having at least one chemical element (eg, xenon, lithium, or tin) into a plasma state using one or more emission lines in the EUV range. In one such method, the desired plasma, often referred to as laser-produced plasma ("LPP"), can be produced by irradiating a droplet of material such as a material having the desired line-emitting element with a laser beam. Fuel is produced. The EUV source SO may be part of an EUV radiation source including a laser (not shown in Figure 1 ) used to provide a laser beam that excites the fuel. The resulting plasma emits output radiation, such as EUV radiation, which is collected using a radiation collector disposed in the EUV source.

For example, when a _CO2 laser is used to provide a laser beam for fuel excitation, the laser and EUV source may be separate entities. In these cases, the radiation beam is delivered from the laser to the EUV source by means of a beam delivery system including, for example, suitable guide mirrors and/or beam expanders. Laser and fuel supplies can be considered to contain sources of EUV radiation.

The illuminator IL may comprise an adjuster for adjusting the angular intensity distribution of the radiation beam. Generally speaking, at least an outer radial extent and/or an inner radial extent (commonly referred to as σ outer and σ inner respectively) of the intensity distribution in the pupil plane of the illuminator can be adjusted. Additionally, the illuminator IL may include various other components, such as faceted field mirror devices and faceted pupil mirror devices. The illuminator can be used to adjust the radiation beam to have a desired uniformity and intensity distribution in its cross-section.

The radiation beam PB is incident on and patterned by the patterning device (eg, mask) MA, which is held on a support structure (eg, mask table) MT. Patterning device MA may be positioned using a first positioning device such as interferometer IF1 and mask alignment marks M1, M2. After reflection from the patterning device (eg, mask) MA, the patterned radiation beam PB passes through the projection system PS, which focuses the beam onto a target portion C of the substrate W. By means of a second positioning device such as an interferometer IF2 and substrate alignment marks P1, P2 (for example using an interferometric device, a linear encoder or a capacitive sensor), the substrate table WT can be accurately moved, for example, in order to align different targets Portion C is positioned in the path of radiation beam PB.

The device depicted can be used in at least one of the following modes:

1. In step mode, the support structure (e.g., mask table) MT and substrate table WT are kept substantially stationary while the entire pattern imparted to the radiation beam is projected onto the target portion C at once (i.e., single static exposure). Next, the substrate table WT is displaced in the X and/or Y directions so that different target portions C can be exposed.

2. In scanning mode, the support structure (eg, mask table) MT and substrate table WT are scanned simultaneously while projecting the pattern imparted to the radiation beam onto the target portion C (ie, a single dynamic exposure). The speed and direction of the substrate table WT relative to the support structure (eg, mask table) MT can be determined by the magnification (reduction ratio) and image reversal characteristics of the projection system PS.

3. In another mode, the support structure (eg, masking table) MT is held substantially stationary, thereby holding the programmable patterning device, and the substrate table WT is moved or scanned while imparting the pattern to the radiation beam. Project onto target part C. In this mode, a pulsed radiation source is typically used, and the programmable patterning device is updated as needed after each movement of the substrate table WT or between sequential radiation pulses during a scan. This mode of operation can be readily applied to maskless lithography utilizing programmable patterning devices, such as programmable mirror arrays of the type mentioned above.

Figure 2 shows schematically a known device. The apparatus of Figure 2 includes a first chamber 101 containing an illumination system IL and a projection system PS. The illumination system IL is configured to condition the radiation beam received from the source SO, and the projection system PS is configured to project the patterned radiation beam PB onto a target portion of the substrate W. The first chamber 101 also contains a patterning device support configured to support a patterning device MA capable of imparting a pattern to the radiation beam in its cross-section to form a patterned radiation beam. The second chamber 102 contains the wafer stage, with only substrate W shown for clarity.

Figure 2 shows how the equipment can be divided into four different vacuum environments VE1 to VE4. The first chamber 101 defines a first vacuum environment VE1 enclosing a patterning device stage of the patterning device MA only shown for clarity. The first chamber 101 also includes a partition structure 103 defining two other vacuum environments: VE2 housing the lighting system IL and VE3 housing the projection system PS. Vacuum environments can be further divided into VE2 and VE3. The baffle construction 103 includes a sleeve 105 having a structure for delivering the projection beam PB from the illumination system IL to the patterning device MA, and for delivering the patterned radiation beam from the patterning device MA to the projection system PS. An aperture of 104. The sleeve 105 is also used to force the airflow downward (ie, away from the patterning device) and to maintain uniform airflow to avoid interference with EUV radiation intensity. It is possible that the sleeve can be tapered towards the patterning device MA. The second chamber 102 defines a vacuum environment VE4 and a wafer stage (only substrate W is shown for clarity). The vacuum environments VE1 and VE2 are formed and maintained by respective vacuum containers and vacuum pumps VP1 and VP2 (which can also be a plurality of vacuum pumps).

As shown in Figure 2 , the vacuum pump VP1 maintains the vacuum environment VE1 at a lower pressure than the vacuum environments VE2 and VE3. A gas injector (not shown in the figure) is used to inject clean gas (for example, hydrogen, nitrogen, oxygen or argon) into the vacuum environments VE2 and VE3. Such vacuum pumps VP1, VP2 are known to those skilled in the art and can be coupled to the device in various ways.

The baffle structure 103 may be configured in various ways, and may include, for example, a sleeve 105 extending toward the patterning device MA, at the end of which a projection beam aperture 104 is provided extending toward the patterning device MA. The sleeve 105 carrying the aperture 104 may have a tapering cross-section.

Referring to Figures 1 and 2 , components of a lithography apparatus for performing a lithography process using EUV radiation are described above.

The performance of a vacuum tool depends on the cleanliness of the vacuum environment within the vacuum tool. This is particularly important for EUV vacuum tools, such as an EUV lithography equipment, where a very clean vacuum environment is required over a large dynamic range. Any contaminant gas in the vacuum environment can seriously damage any optical components in the vacuum environment. A contaminant gas as referred to herein may be any gas in any form that when present in amounts above the allowable level of the gas may potentially be detrimental to the performance of the vacuum tool. The levels and/or types of gases present in each of the vacuum environments therefore need to be closely monitored. The usability of EUV vacuum tools depends on the state of the vacuum environment, since the EUV beam should not be turned on if the level of any gas present is not within the operating specifications (i.e., below the maximum allowable level) . When the levels of any gases present are not within operating specifications, the vacuum environment of the EUV vacuum tool needs to be readjusted to prevent excessive damage to optical or other components.

The type and level of gases in the vacuum environment of EUV vacuum tools can be monitored by a residual gas analyzer (RGA). RGA is a mass spectrometer used for process control and pollution monitoring in vacuum environments. The RGA can be used to determine whether the EUV vacuum tool is ready for exposure (i.e., the EUV beam can be turned on), monitor the level of contaminant gases within the EUV vacuum tool, and detect any vacuum leaks. RGA can also be used at EUV sources, for example to determine if it is suitable for use where a heater is turned on.

Known implementations of RGA include ion sources, sample chambers containing rarefied gases, ion accelerators, and deep vacuum chambers. The ion source may include an ion generating filament that is an electron emitter. The ion-generating filament can be a cathode that emits electrons when it is heated. Electrons from the ion source are accelerated toward the anode. Electrons enter the sample chamber through one or more openings in the wall of the sample chamber and ionize gas molecules within the sample chamber. The ion accelerator extracts the resulting ions from the sample chamber and focuses them into an ion beam that is ejected into a deep vacuum chamber. In a deep vacuum chamber, ions can be separated by a filter (such as a quadrupole mass filter) depending on their mass-to-charge ratio, and then detected by a detector. The deep vacuum chamber may contain one or more mass analysis instruments for analyzing and/or detecting ions. Specifically, upon passing through the filter, an output current may be generated that is a measure of the abundance of ions with a given mass-to-charge ratio that have passed through the filter. The current can be measured by a detector such as a Faraday cup or a secondary electron multiplier tube. The RGA can, for example, generate and output a spectrum showing the mass and concentration of the detected ions. RGA thus allows the detection, measurement and monitoring of gases in vacuum environments.

As previously described with reference to Figure 2 , an EUV vacuum tool may contain a plurality of vacuum environments. Each vacuum environment within the EUV vacuum tool may contain an RGA such that the EUV vacuum tool contains a plurality of RGAs. A single vacuum environment within an EUV vacuum tool can contain multiple RGAs. For example, if the vacuum environment within the EUV vacuum tool contains more than one set of optical components, a separate RGA may be positioned proximate to each set of optical components.

The use of one or more RGAs in an EUV vacuum tool thus allows the detection, measurement and monitoring of gases within the EUV vacuum tool. In response to gas detection, measurement and/or monitoring, if contaminant gases are detected and/or the measured level of contaminant gases is higher than the allowable level, perform readjustment operations and/or any other appropriate action.

Figure 3 shows the known RGA. The RGA includes a sample chamber 304, an ion accelerator 315, and a deep vacuum chamber 312.

Detection chamber 312 contains ion source 310 . Ion source 310 may be an ion-generating filament configured to emit electrons. Each ion-generating filament may serve as a cathode. Detection chamber 312 may be configured to accelerate electrons from each ion source 310 toward the anode. Although two ion sources 310 are shown in Figure 3 , implementations include the use of only one ion source 310, or more than two ion sources 310. Preferably, there are a plurality of ion sources 310 so that the operational lifetime of the RGA is not dependent on just one ion source 310.

The detection chamber 312 may include a quadrupole mass filter, a Faraday cup, and a secondary electron multiplier tube. There may also be one or more other mass analysis instruments used to analyze the ions detected by the Faraday cup and secondary electron multiplier tube. The RGA may be part of an RGA system that also includes a computer system for generating and outputting analysis results. For example, analysis results may include spectra showing the mass and concentration/pressure of the detected ions.

The RGA may include a first vacuum pump 305 configured to pump gas from the internal environment of the vacuum chamber 301 of the vacuum tool through the aperture 313 and into the sample chamber 304 . The RGA may also include a second vacuum pump 306, and additional orifices, so that the pressure in the detection chamber 312 can be maintained below about 5E-5 mbar. An interstage line 314 may exist between the first vacuum pump 305 and the second vacuum pump 306 . The first vacuum pump 305 and the second vacuum pump 306 are configured to generate and maintain appropriate vacuum conditions in the sample chamber 304 and the detection chamber 312, respectively, for the procedures performed therein. The range of vacuum in sample chamber 304 and detection chamber 312 may be the same or different. In particular, the pressure may be lower in detection chamber 312 compared to sample chamber 304. In an alternative implementation, there is only a single vacuum pump used to create and maintain substantial vacuum conditions in sample chamber 304 and detection chamber 312 . The RGA may include one or more pressure gauges 311 for measuring the pressure within the detection chamber 312.

The RGA may contain a sample tube 307. The end 302 of the sample tube 307 is in fluid communication with the internal environment of the vacuum chamber 301 of a vacuum tool, such as an EUV vacuum tool. There may be a pressure gauge 303 for measuring the pressure within the vacuum chamber 301. The other end of sample tube 307 is in fluid communication with the interior of sample chamber 304. Sample tube 307 may include a valve 308 configured to control the flow of gas through sample tube 307 . There may be an orifice 313 at the interface between sample tube 307 and sample chamber 304. Sample chamber 304 can operate at a lower pressure than vacuum chamber 301 and orifice 313 can help support the pressure differential between sample tube 307 and sample chamber 304. For example, the pressure in vacuum chamber 301 may be about 1E-2 mbar and the pressure in sample chamber 304 may be about 1E-3 bar.

The sample chamber 304 may be separated from the detection chamber 312 by a wall containing a minimal opening. Openings in the wall allow ions to flow from the sample chamber 304 and into the detection chamber 312.

One or more pressure gauges 309 may be provided for measuring and monitoring the pressure in the sample chamber 304.

The following is a description of the operation of the RGA shown in Figure 3 . The RGA can operate with an EUV vacuum tool to detect and measure the presence of any gas in the vacuum chamber 301 of the EUV vacuum tool.

Valve 308 can be opened so that any gas within vacuum chamber 301 can flow through sample tube 307 , through orifice 313 and into sample chamber 304 . Sample chamber 304 may be at a lower pressure than vacuum chamber 301 and therefore opening valve 308 generally does not allow gas to flow from sample chamber 304 into vacuum chamber 301 . The sample chamber 304 may also be internally cleaned to prevent any diffusive mass transfer into the vacuum chamber 301 from occurring.

Sample chamber 304 may therefore contain gas received from vacuum chamber 301 . Ion source 310 may emit electrons into sample chamber 304. The emitted electrons may pass through one or more openings in the wall of sample chamber 304. At least some of the gas within sample chamber 304 may be ionized by the emitted electrons. Ions may be accelerated by ion accelerator 315 into an ion beam that is injected into detection chamber 312 . The detector in the detection chamber 312 can detect ions. The output from the RGA may include, for example, a spectrum showing the mass and/or concentration/current of the detected ions, and/or the pressure level of the gas present in the vacuum chamber 301, and/or the amount of partial pressure level. Test.

Therefore, the RGA can detect the presence of gases present in vacuum chamber 301 and can monitor the amount of any contaminant gases. If the amount of pollutant gas exceeds the allowable level, then appropriate action can be taken.

As described above, the RGA may include a Faraday cup and/or a secondary electron multiplier tube configured to detect filtered ions in the detection chamber 312 . Each of these components can output a measurement of the detected ions in the detection chamber 312 . Specifically, the Faraday cup and secondary electron multiplier tube can generate current measurements depending on the detected ions. The pressure and/or partial pressure of the detected ions can be determined based on current measurements. As described above, the RGA may include one or more pressure gauges 311 for measuring the pressure within the detection chamber 312. There may be major gas components present in detection chamber 312 that substantially define the pressure therein. Pressure measurements made by one or more pressure gauges 311 can thus be compared to measured currents for the same primary gas component to thereby map the measured currents to actual pressures and/or partial pressures. The determination of how to map measured current to actual pressure and/or partial pressure may alternatively or additionally be based on measurements from one or more of the other pressure gauges 303, 309. For example, the measured current may be related to the total pressure measured in vacuum chamber 301 by pressure gauge 303 . The measured current peaks for the major gas components can be mapped to the total pressure measured by pressure gauge 303. This mapping can then be used to calculate the partial pressure corresponding to other current peaks.

Figure 4 shows different measurements of filtered ions in the detection chamber 312 made by a Faraday cup and a secondary electron multiplier tube. The main gas component in the detection chamber 312 is hydrogen, shown as H2 in FIG. 4 . For each of the Faraday cup and secondary electron multiplier tubes, the hydrogen peak can be measured and the current measurement mapped to the measured pressure in detection chamber 312. This mapping allows the pressure measurement to be determined for all current measurements so that the pressure of ions other than hydrogen can be determined.

In Figure 4, the y-axis shows the pressure level that has been determined depending on one or more of the current measurements and the pressure gauges 311, 309, 303 measurements. In Figure 4, the x-axis shows the mass of the ion in atomic mass units (AMU). Faraday cups and secondary electron multipliers can measure ion masses within the same range of the AMU.

It should be noted that the general procedures for measuring ion quantities are different in Faraday cups and secondary electron multiplier tubes. Therefore, a current measurement of a hydrogen peak by a Faraday cup will be different from a current measurement of the same hydrogen peak by a secondary electron multiplier tube. To determine the pressure measurement, different mappings for the current measurement of the Faraday cup and the secondary electron multiplier tube are required.

For some applications of RGA (in particular monitoring of scanners or sources of EUV vacuum tools), the main gas component may be hydrogen. The pressure of the secondary gas components, such as oxygen, water, nitrogen and argon, may be 10 ⁴ to 10 ¹⁰ lower than the pressure of the primary gas components. The dynamic range of a detector is the ratio of the largest quantity to the smallest quantity that the detector can measure. Measuring the pressure of both primary and secondary gas components may therefore require a dynamic range of 10 ⁷ or greater.

The dynamic range of the Faraday cup is shown by 401 in Figure 4 and can be 10 ⁴ . The dynamic range of the secondary electron multiplier tube is shown by 402 in Figure 4 and can be 10 ⁷ . The dynamic range of the secondary electron multiplier tube is therefore greater than the dynamic range of the Faraday cup. There is a noise floor difference 403 between the Faraday cup and the secondary electron multiplier tube. The larger dynamic range of the secondary electron multiplier tube allows it to detect the peak value of hydrogen gas and the much lower peak value of water, shown in Figure 4 as H2 and H2O respectively. However, when the Faraday cup is configured to detect the peak value of hydrogen, the Faraday cup cannot detect the peak value of water because the peak value of water is below the noise floor of the Faraday cup. Therefore, in known configurations of RGAs used in EUV vacuum tools, only secondary electron multipliers are used, since they have sufficient dynamic range to detect ions of the primary gas component as well as secondary gas components. The only detector that separates the two ions.

A problem that can be identified using known implementations of RGA in EUV vacuum tools is the need for high-quality secondary electron multipliers with a large dynamic range. The required secondary electron multiplier tubes are expensive components. The desired dynamic range may also be greater than the dynamic range achievable by the secondary electron multiplier tube.

Embodiments provide new configurations of RGAs for use with vacuum tools. Configurations of RGAs according to embodiments may be particularly suitable for use with EUV vacuum tools, such as EUV lithography equipment, and may address at least the issues identified above.

The embodiment effectively increases the dynamic range of RGA. In an embodiment, both the Faraday cup and the secondary electron multiplier tube are used to measure the amount of ions, wherein the Faraday cup and the secondary electron multiplier tube operate in different measurement ranges of the ion amount. The measured ion quantities from the combination of the Faraday cup and the secondary electron multiplier tube are within a greater dynamic range than the individual dynamic ranges of the Faraday cup and the secondary electron multiplier tube.

Embodiments in which hydrogen is the primary gas component and nitrogen is one of the secondary gas components are described below. However, the techniques of the embodiments may be applied with other gases as the primary gas component and/or the secondary gas component.

According to one embodiment, only the Faraday cup is used to measure the peak value of the primary gas component and the peak value of at least one secondary gas component present in the detection chamber 312 . As shown in Figure 5A, a Faraday cup produces a current measurement of the primary gas component, which is hydrogen. The Faraday cup also produces a current measurement of a secondary gas component, which is nitrogen. Although other minor components of the gas are present in the detection chamber 312, they are not detected by the Faraday cup because they are below its noise floor. The pressure corresponding to these current measurements can be determined according to known techniques described above. In other words, the pressure of the detection chamber 312 and/or the vacuum chamber 301 can be measured by one or more pressure gauges 311, 309, 303. This measured pressure can be compared to the measured current for the main gas component to thereby map all of the current measured by the Faraday cup to pressure and/or partial pressure. The pressure and/or partial pressure of the nitrogen secondary gas component can therefore be determined by the current measured by the Faraday cup. The pressure determined by the Faraday cup self-current measurement is shown in Figure 5B.

Unlike known techniques, the dynamic range of the secondary electron multiplier tube is configured to operate mostly in a different quantity measurement range than the dynamic range of the Faraday cup. In detail, as shown in Figure 5A, the secondary electron multiplier tube is configured such that it does not measure the peak value of the primary gas component. The maximum value of the dynamic range of the secondary electron multiplier tube can therefore be set to a level that is substantially smaller than the level required to measure the peak value of the main gas component. The secondary electron multiplier tube is configured to measure the peak value of the secondary gas component. The maximum value of the dynamic range of the secondary electron multiplier tube can therefore be set to a level greater than or equal to the level required to measure the peak value of the secondary gas component.

Figure 5A shows different current measurements using a Faraday cup and a secondary electron multiplier tube. The Faraday cup and the secondary electron multiplier tube have different measured currents for the same peak value of the nitrogen secondary gas component. The current measurement by the secondary electron multiplier tube at the peak of the nitrogen secondary gas component can be mapped to a pressure and/or partial pressure measurement because, as described above, the pressure of the nitrogen secondary gas component can be Faraday cup self-current measurement and determination. This mapping allows all of the current measurements made by the secondary electron multiplier tubes to be mapped to pressure and/or partial pressure measurements. Figure 5B shows all pressure measurements that have been determined for current measurement by the secondary electron multiplier tube.

The secondary electron multiplier tube can also be configured to operate in a different measurement range than the AMU's Faraday cup. As shown in Figures 5A and 5B, the secondary electron multiplier tube can be configured so that it does not measure the peak value of the primary gas component. The maximum peak value measured by the secondary electron multiplier tube can therefore be the peak value of the secondary gas component of nitrogen. The AMU measurement range of the secondary electron multiplier tube may not include any measurement of the main gas components. When the AMU of the primary gas component is lower than the AMU of all secondary gas components, the AMU measurement range of the secondary electron multiplier tube can start at an AMU larger than the AMU of the primary gas component. The AMU measurement range of the secondary electron multiplier tube should be at a lower AMU than the AMU of the secondary gas component measured by the Faraday cup or at the same AMU as the AMU of the secondary gas component measured by the Faraday cup Start at. Preferably, the AMU measurement range of the secondary electron multiplier tube starts only after the AMU of the main gas component. There may be a secondary gas component that is below the noise floor of the Faraday cup and has a lower AMU than the secondary gas component detected by the Faraday cup (i.e. N2 in Figures 5A and 5B) (Such as H2O in Figures 5A and 5B). The secondary electron multiplier can detect such secondary gas components (ie, H2O) when its AMU measurement range begins only after the AMU of the primary gas component. Alternatively, the AMU measurement range of the secondary electron multiplier tube can be configured to start just before the AMU of the secondary gas component measured by the Faraday cup.

5B shows the pressure that has been determined as a function of the current measured by both the Faraday cup and the secondary electron multiplier tube according to the technology of embodiments.

The dynamic range of the Faraday cup (as shown by 401 in Figure 5B) can be configured such that the peak values of the major gas components are measured. The maximum gas level that needs to be measured by the secondary electron multiplier tube is the peak value of the secondary gas component, and not the peak value of the primary gas component. The maximum range of the dynamic range of the secondary electron multiplier tube (as shown by the upper end of 402 in Figure 5B) can therefore be configured to measure pressures much lower than the peak values of the major gas components. The minimum range of the dynamic range of the secondary electron multiplier tube (as shown by the lower end of 402 in Figure 5B) can therefore be configured to be compared to the case where the secondary electron multiplier tube also measures the peak value of the main gas component. Measure much lower pressures.

The dynamic ranges of the Faraday cup and secondary electron multiplier tubes can be combined to provide an effective dynamic range 501, as shown in Figure 5B. Advantageously, the effective dynamic range 501 is greater than the individual dynamic ranges of the Faraday cup and secondary electron multiplier tubes shown as 401 and 402 respectively. The effective dynamic range 501 of the pressure measurement is therefore greater than the dynamic range using known techniques.

Known techniques only use secondary electron multiplier tubes for pressure measurement. Embodiments effectively increase the dynamic range of the RGA by approximately that of a Faraday cup. This provides an increase in dynamic range of approximately 10 ⁴ . Embodiments can thus effectively increase the dynamic range of RGA. Alternatively, embodiments allow the required dynamic range to be achieved using secondary electron multipliers that have a lower dynamic range than currently used and are therefore less expensive.

A further advantage of the embodiment is that the performance of the secondary electron multiplier tube can be attributed to the high flux experienced by ion bombardment as the peak value of the primary gas component is measured, deteriorating over time. When the secondary electron multiplier tube does not measure the peak value of the main gas component, the embodiment can increase the service life of the secondary electron multiplier tube. Faraday cups are very insensitive to degradation when measuring peak values of major gas components.

Embodiments require a Faraday cup to measure both the peak value of a major gas component and the peak value of at least one minor gas component. If a suitable secondary gas component is not present, embodiments include introducing a small amount of gas (detectable as a secondary gas component by a Faraday cup) into the sample chamber 304. For example, the primary gas component may be hydrogen and a small amount of nitrogen may be introduced into sample chamber 304 as a secondary gas component.

As previously described, an EUV vacuum tool can contain a plurality of vacuum environments. Vacuum environments can differ in their maximum allowable pressure. Vacuum environments can also differ in the maximum allowable amount of contaminant gases. According to one or more embodiments, one or more RGAs may be used to monitor pressure and gas volume in various vacuum environments in EUV vacuum tools.

RGA operates over a wide range of pressures. The specific pressure in each RGA case may depend on the vacuum environment monitored by the RGA and the detection requirements of the RGA.

An RGA according to an embodiment may be used in any part of any type of vacuum tool. In particular, RGA can be used with a radiation source such as an EUV source. The EUV source can be used with an EUV vacuum tool such as an EUV lithography equipment.

Embodiments include various modifications of the techniques described above.

Embodiments have been described using a Faraday cup that measures the peaks of the primary gas component and the secondary gas component, and a secondary electron multiplier tube that measures the secondary gas component and does not measure the peak of the primary gas component. Embodiments also include a secondary electron multiplier tube that measures the peak value of the primary gas component and the secondary gas component, and a Faraday cup that measures the secondary gas component but does not measure the peak value of the primary gas component. The same technology can be used to match the current measurement and pressure measurement from each detector.

Embodiments also include using more than one Faraday cup and/or more than one secondary electron multiplier tube. This can be used to additionally extend the dynamic range by using two detectors using the same technology to determine pressure based on measurements of the same gas component. One of the detectors may measure a gas component near the lower limit of its dynamic range and the other detector may measure a gas component near the upper limit of its dynamic range. The dynamic ranges of the detectors can then be combined to effectively provide a greater dynamic range than individual detectors.

Detection of gas components is described throughout the examples. It should be understood that the description of detecting a gas component may refer to detecting ions of the gas component. For example, the detection of hydrogen gas includes the detection of hydrogen ions.

In the above embodiment, the primary gas component is hydrogen and the secondary gas component is nitrogen. Embodiments include alternative configurations of EUV vacuum tools with gases other than the primary gas component. For example, the main gas component may be nitrogen or argon. EUV vacuum tools can also have gases that are different from the secondary gas composition measured by the Faraday cup and secondary electron multiplier tube. For example, the secondary gas component may be hydrogen, oxygen, or water.

As described above, AMU measurements by secondary electron multiplier tubes preferably do not include AMU measurements of major gas components. When the primary gas component is nitrogen and the secondary gas component is hydrogen, the AMU of the primary gas component will be greater than the AMU of the secondary gas component. Therefore, measurements by a secondary electron multiplier tube may include measurements with a lower AMU than the dominant gas component, and also include measurements with an AMU greater than the dominant gas component.

Each detector according to embodiments may be any type of detector capable of measuring ion quantities.

In FIG. 3 , there is an interstage line 314 between the first vacuum pump 305 and the second vacuum pump 306 . Embodiments also include the absence of interstage line 314 between first vacuum pump 305 and second vacuum pump 306 . The RGA is not limited to including two vacuum pumps as shown in Figure 3 . The RGA may alternatively include a single pump with an interstage line so that the same pump can degas both the sample chamber 304 and the detection chamber 312.

In the above embodiment, the pressure measurement in the detection chamber 312 is performed by one or more pressure gauges 311 . Pressure measurements for other areas may alternatively or additionally be obtained by using other pressure gauges, such as one or more pressure gauges 303 and 309.

Embodiments include any use of RGA. For example, embodiments may be used to improve RGA for monitoring gases in other types of tools besides EUV vacuum tools.

The dynamic range of a Faraday cup can be a fixed setting that is not tunable. In this case, the embodiment only changes the dynamic range of the secondary electron multiplier tube.

Figures 5A and 5B show current and pressure measurements, respectively, relative to the measurement range which is the AMU measurement range. Embodiments also include a measurement range that is the AMU charge ratio measurement range. In other words, the detector can measure AMU/charge and these can be the x-axis in Figures 5A and 5B. If the detected ion has a single charge, the ion's AMU charge ratio is the same as the ion's AMU. When an ion has double or more charges, the AMU charge ratio of the ion will be different from the AMU of the ion.

Examples include the following numbered items: 1. A residual gas analyzer RGA for determining the amount of gas components in a vacuum tool. The RGA includes a first detector and a second detector, wherein: The first detector is configured such that the maximum amount of gas component that can be determined by the first detector is greater than the maximum amount of gas component that can be determined by the second detector; The first detector is configured such that the minimum gas component amount that can be determined by the first detector is less than or equal to the maximum gas component amount that can be determined by the second detector; and The second detector is configured such that the minimum gas component amount that can be determined by the second detector is less than the minimum gas component amount that can be determined by the first detector. 2. As in the RGA of Item 1, where: the first detector is configured to determine both a maximum amount of a primary gas component and a maximum amount of a secondary gas component; The second detector is configured to determine the maximum amount of the secondary gas component; and The second detector is configured such that the maximum amount of gas component that can be determined by the second detector is less than the maximum amount of the primary gas component. 3. The RGA of clause 1 or 2, wherein the RGA is configured to output a measurement of the gas component amount determined by the first detector and the second detector. 4. If any of the foregoing provisions of the RGA, where: The first detector is configured to output current as the determined gas component amounts; and/or The second detector is configured to output current as the determined gas component amounts. 5. An RGA as in any of the preceding clauses, wherein the second detector is configured such that its atomic mass unit AMU, measurement range or its AMU charge ratio measurement range does not include an amount of the main gas component Test. 6. An RGA as in any of the preceding clauses, wherein the second detector is configured such that its AMU measurement range or its AMU charge ratio measurement range includes measurements that are slightly larger than the measurement of the main gas component. . 7. The RGA of any preceding clause, wherein the second detector is configured such that its AMU measurement range or AMU charge ratio measurement range includes AMUs that are slightly smaller than the AMUs of the main gas component. 8. An RGA as in any of the preceding clauses, wherein the first detector is a Faraday cup and the second detector is a secondary electron multiplier tube. 9. A residual gas analyzer RGA system for determining the pressure of gas components in a vacuum tool, the RGA system includes: If any of the foregoing provisions of the RGA; and a computer system; in: The computer system is configured to receive first and second current measurements from the first detector of the RGA, wherein the first current measurement is a determined amount of a major gas component and the second current measurement measured as a determined quantity of a primary gas component; the computer system is configured to receive a third current measurement from the second detector of the RGA, wherein the third current measurement is the secondary gas component One-third of the judged amount; the computer system is configured to receive a pressure measurement substantially of the pressure of the primary gas component; The computer system is configured to determine, depending on the received pressure measurement and the received first current measurement, the pressure corresponding to the current measurement received from the first detector such that the second The pressure of the gas component is determined; and The computer system is configured to determine a pressure corresponding to the current measurement received from the second detector depending on the determined pressure of the second gas component and the received third current measurement. 10. The RGA system of clause 9, wherein the RGA system is configured to output the determined pressure depending on the current measured by both the first detector and the second detector. 11. The RGA system of clause 9 or 10, wherein the effective dynamic range of the pressures determined by the RGA system is greater than the dynamic range of the pressures that can be determined by the first detector; and The effective dynamic range of the pressures determined by the RGA system is greater than the dynamic range of pressures that can be determined by the second detector. 12. A method for determining gas composition by a residual gas analyzer RGA in a vacuum tool, the method includes: operating a first detector such that the maximum gas component amount that can be determined by the first detector is greater than the maximum gas component amount that can be determined by a second detector; operating the first detector such that the minimum gas component amount that can be determined by the first detector is less than or equal to the maximum gas component amount that can be determined by the second detector; and The second detector is operated such that the minimum gas component amount that can be determined by the second detector is less than the minimum gas component amount that can be determined by the first detector. 13. The method of Clause 12, wherein the RGA is an RGA as in any one of Clauses 1 to 8, or an RGA in an RGA system as in any one of Clauses 9 to 11. 14. A computer implementation method for measuring and determining pressure from a residual gas analyzer RGA, which method includes: Receive first and second current measurements from a first detector of the RGA, wherein the first current measurement is a determined amount of a primary gas component and the second current measurement is a primary gas component a judged quantity; receiving a third current measurement from the second detector of the RGA, wherein the third current measurement is a determined amount of the secondary gas component; receiving a pressure measurement that is substantially the pressure of the primary gas component; Determining, by the first detector, a pressure corresponding to the received pressure measurement and the received first current measurement, such that the pressure of the second gas component is determined; and The pressure corresponding to the current measurement is determined by the second detector depending on the determined pressure of the second gas component and the received third current measurement. 15. A charged particle device comprising a residual gas analyzer RGA according to any one of clauses 1 to 8, or an RGA system according to any one of clauses 9 to 11. 16. The charged particle equipment of item 15, wherein the charged particle equipment is an EUV tool.

Although specific reference may be made herein to embodiments of the invention in the context of lithography equipment, embodiments of the invention may be used in other equipment. Embodiments of the present invention may form components of mask inspection equipment, metrology equipment, or any equipment that measures or processes items such as wafers (or other substrates) or masks (or other patterned devices). Such equipment may generally be referred to as lithography tools. This lithography tool can be used under vacuum conditions or ambient (non-vacuum) conditions.

The term "EUV radiation" may be considered to encompass electromagnetic radiation having a wavelength in the range of 4 nm to 20 nm, for example in the range of 13 nm to 14 nm. EUV radiation may have a wavelength less than 10 nm, for example, a wavelength in the range of 4 nm to 10 nm, such as 6.7 nm or 6.8 nm.

Although specific reference may be made herein to the use of lithography equipment in IC fabrication, it should be understood that the lithography equipment described herein may have other applications. Possible other applications include the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat panel displays, liquid crystal displays (LCDs), thin film magnetic heads, etc.

While specific embodiments of the invention have been described above, it will be understood that the invention may be practiced otherwise than as described. The above description is intended to be illustrative and not restrictive. It will therefore be apparent to those skilled in the art that modifications can be made to the invention described without departing from the scope of the claims as set forth below.

101:First chamber 102:Second chamber 103:Partition structure 104:Aperture 105: Casing 301: Vacuum chamber 302:End 303: Pressure gauge 304:Sample chamber 305:First vacuum pump 306: Second vacuum pump 307:Sample tube 308:Valve 309: Pressure gauge 310:Ion source 311: Pressure gauge 312:Deep vacuum chamber 313:orifice 314: Interstage line 315:Ion accelerator 401:Dynamic range 402:Dynamic range 403: Noise floor difference 501: Effective dynamic range 502:Dynamic range C: Target part IF1: Interferometer IF2: Interferometer IL: illuminator MA: Patterned installation MT: support structure M2: Mask alignment mark M1: Mask alignment mark PB: Radiation beam/Projection beam PM: first locator PS:Projection system PW: Second locator P1: Substrate alignment mark P2: Substrate alignment mark SO: Source Collector Module/EUV Source VE1: Vacuum environment VE2: Vacuum environment VE3: Vacuum environment VE4: Vacuum environment VP1: Vacuum pump VP2: Vacuum pump W: substrate WT: substrate table

The accompanying drawings, which are incorporated in and form part of this specification, illustrate the invention and, together with the embodiments, further explain the principles of the invention and enable those skilled in the relevant art to make and use the invention.

Figure 1 schematically depicts a known lithography apparatus;

Figure 2 shows the pressure area of a known lithography equipment;

Figure 3 shows the known RGA;

Figure 4 shows the measurement of ions by a Faraday cup and a secondary electron multiplier tube according to known technology;

Figure 5A shows current measurement of ions by a Faraday cup and a secondary electron multiplier tube according to one embodiment; and

FIG. 5B shows pressure measurement of ions performed by a Faraday cup and a secondary electron multiplier tube according to one embodiment.

401:Dynamic range

402:Dynamic range

501: Effective dynamic range

502:Dynamic range

Claims (16)

A residual gas analyzer RGA for determining the amount of gas components in a vacuum tool. The RGA includes a first detector and a second detector, wherein: The first detector is configured such that the maximum amount of gas component that can be determined by the first detector is greater than the maximum amount of gas component that can be determined by the second detector; The first detector is configured such that the minimum gas component amount that can be determined by the first detector is less than or equal to the maximum gas component amount that can be determined by the second detector; and The second detector is configured such that the minimum gas component amount that can be determined by the second detector is less than the minimum gas component amount that can be determined by the first detector. Such as the RGA of request item 1, where: the first detector is configured to determine both a maximum amount of a primary gas component and a maximum amount of a secondary gas component; The second detector is configured to determine the maximum amount of the secondary gas component; and The second detector is configured such that the maximum amount of gas component that can be determined by the second detector is less than the maximum amount of the primary gas component. The RGA of claim 1 or 2, wherein the RGA is configured to output a measurement of the gas component amount determined by the first detector and the second detector. Such as the RGA of request item 1 or 2, where: The first detector is configured to output current as the determined gas component amounts; and/or The second detector is configured to output current as the determined gas component amounts. The RGA of claim 1 or 2, wherein the second detector is configured such that its atomic mass unit AMU, measurement range, or its AMU charge ratio measurement range does not include one of the measurements of the main gas component. The RGA of claim 1 or 2, wherein the second detector is configured such that its AMU measurement range or its AMU charge ratio measurement range includes measurements slightly larger than the measurement of the main gas component. The RGA of claim 1 or 2, wherein the second detector is configured such that its AMU measurement range or AMU charge ratio measurement range includes AMUs that are slightly smaller than the AMUs of the main gas component. The RGA of claim 1 or 2, wherein the first detector is a Faraday cup and the second detector is a secondary electron multiplier tube. A residual gas analyzer RGA system for determining the pressure of gas components in a vacuum tool, the RGA system includes: If any of the foregoing claims is RGA; and a computer system; in: The computer system is configured to receive first and second current measurements from the first detector of the RGA, wherein the first current measurement is a determined amount of a major gas component and the second current measurement Measured as a determined quantity of one of the primary gas components; The computer system is configured to receive a third current measurement from the second detector of the RGA, wherein the third current measurement is a determined amount of the secondary gas component; the computer system is configured to receive a pressure measurement substantially of the pressure of the primary gas component; The computer system is configured to determine, depending on the received pressure measurement and the received first current measurement, the pressure corresponding to the current measurement received from the first detector such that the second The pressure of the gas component is determined; and The computer system is configured to determine a pressure corresponding to the current measurement received from the second detector depending on the determined pressure of the second gas component and the received third current measurement. The RGA system of claim 9, wherein the RGA system is configured to output the determined pressure depending on the current measured by both the first detector and the second detector. The RGA system of claim 9 or 10, wherein the effective dynamic range of the pressures determined by the RGA system is greater than the dynamic range of the pressures that can be determined by the first detector; and The effective dynamic range of the pressures determined by the RGA system is greater than the dynamic range of pressures that can be determined by the second detector. A method for determining gas composition by a residual gas analyzer RGA in a vacuum tool, the method includes: operating a first detector such that the maximum gas component amount that can be determined by the first detector is greater than the maximum gas component amount that can be determined by a second detector; operating the first detector such that the minimum gas component amount that can be determined by the first detector is less than or equal to the maximum gas component amount that can be determined by the second detector; and The second detector is operated such that the minimum gas component amount that can be determined by the second detector is less than the minimum gas component amount that can be determined by the first detector. The method of claim 12, wherein the RGA is the RGA of any one of claims 1 to 8, or one of the RGAs in the RGA system of any one of claims 9 to 11. A computer-implemented method for determining pressure from residual gas analyzer RGA measurement, the method includes: Receive first and second current measurements from a first detector of the RGA, wherein the first current measurement is a determined amount of a primary gas component and the second current measurement is a primary gas component a judged quantity; receiving a third current measurement from the second detector of the RGA, wherein the third current measurement is a determined amount of the secondary gas component; receiving a pressure measurement that is substantially the pressure of the primary gas component; Determining by the first detector a pressure corresponding to the received pressure measurement and the received first current measurement such that the pressure of the second gas component is determined; and The pressure corresponding to the current measurement is determined by the second detector depending on the determined pressure of the second gas component and the received third current measurement. A charged particle equipment comprising a residual gas analyzer RGA as in any one of claims 1 to 8, or an RGA system as in any one of claims 9 to 11. The charged particle device of claim 15, wherein the charged particle device is an EUV tool.