Sensitive determination of the Young's modulus of thin films by polymeric microcantilevers

Paolo Colombi, Paolo Bergese, Elza Bontempi, Laura Borgese, Stefania Federici, Stephan Sylvest Keller, Anja Boisen, Laura Eleonora Depero

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    A method for the highly sensitive determination of the Young's modulus of TiO2 thin films exploiting the resonant frequency shift of a SU-8 polymer microcantilever (MC) is presented. Amorphous TiO2 films with different thickness ranging from 10 to 125 nm were grown at low temperature (90 °C) with subnanometer thickness resolution on SU-8 MC arrays by means of atomic layer deposition. The resonant frequencies of the MCs were measured before and after coating and the elastic moduli of the films were determined by a theoretical model developed for this purpose. The Young's modulus of thicker TiO2 films (>75 nm) was estimated to be about 110 GPa, this value being consistent with the value of amorphous TiO2. On the other hand we observed a marked decrease of the Young's modulus for TiO2 films with a thickness below 50 nm. This behavior was found not to be related to a decrease of the film mass density, but to surface effects according to theoretical predictions on size-dependent mechanical properties of nano- and microstructures.

    Original languageEnglish
    JournalMeasurement Science and Technology
    Volume24
    Issue number12
    Pages (from-to)125603
    ISSN0957-0233
    DOIs
    Publication statusPublished - 2013

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