ISO/TS 20175:2018
(Main)Vacuum technology — Vacuum gauges — Characterization of quadrupole mass spectrometers for partial pressure measurement
Vacuum technology — Vacuum gauges — Characterization of quadrupole mass spectrometers for partial pressure measurement
This document describes procedures to characterize quadrupole mass spectrometers (QMSs) with an ion source of electron impact ionization and which are designed for the measurement of atomic mass-to-charge ratios m/z This document is not applicable to QMSs with other ion sources, such as chemical ionization, photo-ionization or field ionization sources and for the measurements of higher m/z, which are mainly used to specify organic materials. It is well known from published investigations on the metrological characteristics of quadrupole mass spectrometers that their indications of partial pressures depend significantly on the settings of the instrument, the total pressure, and the composition of the gas mixture. For this reason, it is not possible to calibrate a quadrupole mass spectrometer for all possible kinds of use. The characterization procedures described in this document cover the applications of continuous leak monitoring of a vacuum system, leak rate measurement with tracer gas, residual gas analysis and outgassing rate measurements. The user can select that characterization procedure that best suits his or her needs. These characterization procedures can also be useful for other applications. It is also well known that the stability of several parameters of quadrupole mass spectrometers, in particular sensitivity, are rather poor. Therefore, when a parameter has been calibrated, it needs frequent recalibration when accuracy is required. For practical reasons this can only be accomplished by in situ calibrations. To this end, this document not only describes how a quadrupole mass spectrometer can be calibrated by a calibration laboratory or a National Metrological Institute with direct traceability to the System International (SI), but also how calibrated parameters can be frequently checked and maintained in situ. By their physical principle, quadrupole mass spectrometers need high vacuum within the instrument. By reducing dimensions or by special ion sources combined with differential pumping the operational range can be extended to higher pressures, up to atmospheric pressure. This document, however, does not include quadrupole mass spectrometers with differential pumping technology. Therefore, it does not cover pressures exceeding 1 Pa on the inlet flange of the quadrupole mass spectrometer. This document does not describe how the initial adjustment of a quadrupole mass spectrometer by the manufacturer or by a service given order by the manufacturer should be made. The purpose of such an initial adjustment is mainly to provide a correct m/z scale, constant mass resolution or constant transmission, and is very specific to the instrument. Instead, it is assumed for this document that a manufacturer's readjustment procedure exists which can be carried on-site by a user. This procedure is intended to ensure that the quadrupole mass spectrometer is in a well-defined condition for the characterization. It is the intention of this document that the user gets the best possible metrological quality from his quadrupole mass spectrometer. From investigations it is known that in most cases this can be achieved in the so called "scan mode". The bar graph may also be of an adequate quality depending on the software used for evaluation of the data taken by the quadrupole mass spectrometer. The trend mode, however, often involves the additional uncertainty that a shift of the peak value position on the mass scale causes a shift in ion current. For this reason, the scan mode is preferable for most of the measurement procedures of this document. It is not the intent of this document that all the parameters described be determined for each quadrupole mass spectrometer. However, it is intended that the value of a parameter addressed in this document be determined according to the procedure described in this document if it is given or measured (e.g. for an inspection test). It is assumed for this document that the applicant
Technique du vide — Manomètres à vide — Description des spectromètres de masse quadripolaires pour mesurage de la pression partielle
General Information
Standards Content (Sample)
TECHNICAL ISO/TS
SPECIFICATION 20175
First edition
2018-04
Vacuum technology — Vacuum gauges
— Characterization of quadrupole
mass spectrometers for partial
pressure measurement
Technique du vide — Manomètres à vide — Description des
spectromètres de masse quadripolaires pour mesurage de la pression
partielle
Reference number
©
ISO 2018
© ISO 2018
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ii © ISO 2018 – All rights reserved
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 2
3 Terms and definitions . 2
4 Symbols and abbreviated terms . 3
5 Parameters for which characterization is required or recommended for the
different applications . 4
5.1 General . 4
5.2 General characterization of the QMS . 5
5.3 Leak rate measurement and leak rate monitoring (helium leak) . 5
5.4 Leak rate monitoring (air leak) . 5
5.5 Leak rate monitoring (water leak) . 6
5.6 Residual gas analysis . 6
5.7 Outgassing rate measurement . 7
6 Vacuum systems to characterize QMS . 7
6.1 General . 7
6.2 Vacuum system for characterization with single gas . 8
6.2.1 Continuous expansion system (orifice flow system) . 8
6.2.2 Calibration system according to ISO 3567:2012 . 8
6.2.3 In situ calibration system . 8
6.3 Vacuum system for characterization with gas mixtures . 9
6.3.1 Continuous expansion system (orifice flow system) . 9
6.3.2 In situ calibration system for gas mixture .10
7 Characterization and calibration procedures .10
7.1 General .10
7.2 Mass resolution .11
7.3 Minimum detectable partial pressure (p ) .12
MDPP
7.4 Minimum detectable concentration (C ) .13
MDC
7.5 Dynamic range.13
7.6 Sensitivity and interference effect ratio .14
7.7 Linear response range .15
7.8 Relative sensitivity factor .15
7.9 Fragmentation pattern (cracking pattern) .16
7.10 Outgassing rate of QMS .16
7.11 Pumping speed of QMS .17
8 Measurement uncertainties .17
8.1 General .17
8.2 Uncertainty of mass resolution .18
8.3 Uncertainty of p .18
MDPP
8.4 Uncertainty of minimum detectable concentration (C ) .18
MDC
8.5 Uncertainty of dynamic range . .18
8.6 Uncertainty of sensitivity .18
8.7 Uncertainty of linear response range .18
8.8 Uncertainty of relative sensitivity factor .18
8.9 Uncertainty of fragmentation factor.18
8.10 Uncertainties of outgassing rate and pumping speed .19
8.11 Long-term stability of characteristic parameters of QMS .19
9 Reporting results .19
Annex A (informative) Estimate of gas composition in the measurement chamber from
known gas composition in the reservoir in front of a leak element under different
flow conditions .21
Bibliography .23
iv © ISO 2018 – All rights reserved
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
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electrotechnical standardization.
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described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
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This document was prepared by Technical Committee ISO/TC 112, Vacuum technology.
Introduction
Quadrupole mass spectrometers (QMSs) are nowadays used not only in vacuum technology for leak
detection and residual gas analysis but also in the process industry as an instrument to provide
quantitative analysis in processes and to control processes such as physical and chemical vapour
deposition, and etch processes. They are also used for quantitative outgassing rate measurements
which are important to characterize vacuum components for critical applications like in the EUV
lithography, semiconductor industry or medical instruments.
Total pressure, composition of the gas mixture, settings and the operational history of QMSs, to name
a few, have a significant influence on the measured signal, its uncertainty and interpretation. For this
reason, it is not possible to calibrate QMS for all its possible applications. Instead, it has either to be
calibrated for the special conditions at use or for a standardized condition. It is the purpose of this
document to establish such conditions.
There is also a need for standardization in order to enable the users of QMSs to compare the devices of
different manufactures and to use the QMS properly.
This document provides standardized calibration procedures for QMSs for some important applications.
These have been selected from the results of a survey of the international project EMRP (European
Metrological Research Programme) IND12 which was conducted in 2013. This survey included
manufacturers, distributors and users of quadrupole mass spectrometers.
vi © ISO 2018 – All rights reserved
TECHNICAL SPECIFICATION ISO/TS 20175:2018(E)
Vacuum technology — Vacuum gauges — Characterization
of quadrupole mass spectrometers for partial pressure
measurement
1 Scope
This document describes procedures to characterize quadrupole mass spectrometers (QMSs) with an
ion source of electron impact ionization and which are designed for the measurement of atomic ma
...
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