Sub-kHz traceable characterization of stroboscopic scanning white light interferometer

V. Heikkinen, I. Kassamakov, T. Paulin, A. Nolvi, J. Seppä, A. Lassila, E. Hæggström

    Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

    1 Citation (Scopus)

    Abstract

    Scanning white light interferometry (SWLI) is an established methodology for non-destructive testing of MEMS/NEMS. In contrast to monochromatic interference microcopy SWLI can unambiguously resolve surfaces featuring tall vertical steps. Oscillating samples can be imaged using a stroboscopic SWLI (SSWLI) equipped with a pulsed light source. To measure static samples the lateral and vertical scales of the SSWLI can be calibrated using transfer standards with calibrated dimensions such as line scales, 2D gratings, gauge blocks, and step height standards. However, traceable dynamic characterization of SSWLI requires a transfer standard (TS) providing repeatable traceable periodic movement. A TS based on a piezo-scanned flexure guided stage with capacitive feedback was designed and manufactured. The trajectories of the stage motion for different amplitude and frequency settings were characterized to have 2 nm standard uncertainty. Characterization was made using a symmetric differential heterodyne laser interferometer (SDHLI). The TS was first used to characterize quasidynamic measurements across the vertical range of the SSWLI, 100 μm. Dynamic measurement properties of the SSWLI were then characterized using a sinusoidal vertical trajectory with 2 μm nominal amplitude and 50 Hz frequency. The motion amplitude of the TS, 2038 nm, measured with the SSWLI was 6 nm smaller than the amplitude measured with SDHLI. The repeatability of SSWLI expressed as experimental standard deviation of the mean was 8.8 nm. The maximum deviation in instantaneous displacement and oscillation velocity were 49 nm and 27 μm/s, respectively. A traceable method to characterize the capacity of the SSWLI to perform dynamic measurements at sub-kHz frequencies was demonstrated.

    Original languageEnglish
    Title of host publicationOptical Micro- and Nanometrology V
    PublisherInternational Society for Optics and Photonics SPIE
    ISBN (Electronic)978-162841080-8
    DOIs
    Publication statusPublished - 2014
    MoE publication typeA4 Article in a conference publication
    EventOptical Micro- and Nanometrology V - Brussels, Belgium
    Duration: 15 Apr 201417 Apr 2014

    Publication series

    SeriesProceedings of SPIE
    Volume9132
    ISSN0277-786X

    Conference

    ConferenceOptical Micro- and Nanometrology V
    Country/TerritoryBelgium
    CityBrussels
    Period15/04/1417/04/14

    Keywords

    • MEMS
    • NEMS
    • SSWLI
    • Traceability

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