Traceability for nanometre scale measurements: Atomic force microscopes in dimensional nanometrology: Dissertation

Research output: ThesisDissertationCollection of Articles

Abstract

Reliability of measurement is a crucial element of both research and industry. Metrological traceability to the SI unit metre guarantees commensurate units, also at nanometre range. In this thesis, a traceability chain is established for nanometre scale measurements. Measurement instruments and methods were developed for accurate measurements, calibration of instruments and transfer standards, and uncertainty estimations. A metrological atomic force microscope (MAFM) was developed and characterized. The MAFM can be used in the calibration of transfer standards and in accurate AFM measurements. Calibration methods for commercial AFMs were developed. A laser diffractometer was also developed for accurate calibration of 1-D and 2-D gratings with a standard uncertainty of several tens of picometres. Laser interferometric position measurement with a calibrated vacuum wavelength is directly traceable to the realization of the metre if measuring full interferometer fringes, but there is small nonlinearity in sub-fringe measurements. Therefore, in sub-nanometre measurements the nonlinearity of the interferometer needs to be corrected. A method for this correction was developed. Laser diffraction measurement is a very accurate method for characterization of grating pitch. One of the main uncertainty sources is the uncertainty of the measured diffraction angle. Therefore, a method for calibration of the rotary table of the laser diffraction setup was developed. The method can be used also in the realization of angle scale. Methods for transfer standard calibration were developed for both pitch and step height calibration by MAFM. An acoustic method was developed for compensation of the refractive index of air in interferometric measurements. Sub-nanometre uncertainty can be reached with this method. Characterization of instruments, validation of methods and uncertainty estimations are a crucial part of traceability. Therefore, uncertainty estimates based on the characterization of the instruments are given for all measurements in this thesis. Comparisons between laboratories are the best way to ensure commensurate measurements. International comparison results between national metrology institutes for pitch and step height transfer standards are listed.
Original languageEnglish
QualificationDoctor Degree
Awarding Institution
  • University of Helsinki
Supervisors/Advisors
  • Lassila, Antti, Supervisor
Award date26 Nov 2014
Place of PublicationHelsinki
Publisher
Print ISBNs978-952-6682-20-4
Electronic ISBNs978-952-6682-21-1
Publication statusPublished - 2014
MoE publication typeG5 Doctoral dissertation (article)

Fingerprint

microscopes
theses
lasers
interferometers
nonlinearity
diffraction
atomic force microscopy
gratings
International System of Units
diffractometers
metrology
industries
refractivity
vacuum
acoustics
air
estimates

Keywords

  • metrology
  • reliability

Cite this

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title = "Traceability for nanometre scale measurements: Atomic force microscopes in dimensional nanometrology: Dissertation",
abstract = "Reliability of measurement is a crucial element of both research and industry. Metrological traceability to the SI unit metre guarantees commensurate units, also at nanometre range. In this thesis, a traceability chain is established for nanometre scale measurements. Measurement instruments and methods were developed for accurate measurements, calibration of instruments and transfer standards, and uncertainty estimations. A metrological atomic force microscope (MAFM) was developed and characterized. The MAFM can be used in the calibration of transfer standards and in accurate AFM measurements. Calibration methods for commercial AFMs were developed. A laser diffractometer was also developed for accurate calibration of 1-D and 2-D gratings with a standard uncertainty of several tens of picometres. Laser interferometric position measurement with a calibrated vacuum wavelength is directly traceable to the realization of the metre if measuring full interferometer fringes, but there is small nonlinearity in sub-fringe measurements. Therefore, in sub-nanometre measurements the nonlinearity of the interferometer needs to be corrected. A method for this correction was developed. Laser diffraction measurement is a very accurate method for characterization of grating pitch. One of the main uncertainty sources is the uncertainty of the measured diffraction angle. Therefore, a method for calibration of the rotary table of the laser diffraction setup was developed. The method can be used also in the realization of angle scale. Methods for transfer standard calibration were developed for both pitch and step height calibration by MAFM. An acoustic method was developed for compensation of the refractive index of air in interferometric measurements. Sub-nanometre uncertainty can be reached with this method. Characterization of instruments, validation of methods and uncertainty estimations are a crucial part of traceability. Therefore, uncertainty estimates based on the characterization of the instruments are given for all measurements in this thesis. Comparisons between laboratories are the best way to ensure commensurate measurements. International comparison results between national metrology institutes for pitch and step height transfer standards are listed.",
keywords = "metrology, reliability",
author = "Virpi Korpelainen",
note = "MIKES",
year = "2014",
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isbn = "978-952-6682-20-4",
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school = "University of Helsinki",

}

Traceability for nanometre scale measurements: Atomic force microscopes in dimensional nanometrology : Dissertation. / Korpelainen, Virpi.

Helsinki : University of Helsinki, 2014. 61 p.

Research output: ThesisDissertationCollection of Articles

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