Regensburg 2007 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 17: Poster Session I (Nanostructures at Surfaces; Metal Substrates: Epitaxy and Growth; Methods: Scanning Probe Techniques; Phase Transitions)

O 17.39: Poster

Montag, 26. März 2007, 17:30–20:30, Poster C

Measurement of stress in AFM cantilevers by Raman spectroscopy — •Michael Bauer, Alexander M. Gigler, and Robert W. Stark — Crystallography, Dep. Earth and Environmental Sci., Ludwig-Maximilians-Universität München, 80333 München, Germany

The most prominent Raman peak of silicon at 523 wave numbers (1/cm) is known to shift upon stress. The peak shift is caused by a change in the crystal structure of the silicon and, hence, a change in the phonon bands under stress. This shift can be used to measure and visualize the spatial distribution of surface stresses in bent AFM cantilevers. The measurements were done using a confocal Raman microscope with diffraction limited lateral resolution. With a estimated resolution of 0.02 1/cm, the system has a nominal resolution of 9 MPa (shifts up to -12 1/cm were observed). The measured stresses can be compared qualitatively to results from finite elements methods (FEM). In this contribution, the Raman shift observed in the cantilever will be discussed in comparison to the shift introduced by the strain of a Vickers indent. The algebraic sign of the shift depends on the type of strain compressive or tensile. Together with the shift, a broadening of the peak and a lower maximum at the centre occurs. The procedure helps to tailor the cantilever properties such as resonant frequencies or bending shape to desired values.