The study of the residual stress in the 3C-SiC/Si hetero-epitaxy is a crucial step for the development of SiC based sensors and microsystems. In this work, Raman microscopy is used to study the stress distribution on 3C-SiC cantilevers. The shift of transverse optical (TO) mode is linked to the stress fields present in the structures, whereas the full width at half maximum (FWHM) is an index of the lattice order. Micro-Raman map allows an accurate study of stress fields acting on the structure. Along the width of the cantilever, a trend of the TO Raman shift, moving towards higher frequency from the centre to the edges of the microstructure, has been observed. This is ascribed to etching processes removing some SiC portion at cantilever edges. Also, close to the anchorage zone, an undercut region is generated due to Silicon over-etch. The undercut region shows a worst lattice order (increased TO-FWHM) with respect to the unreleased and free standing regions. Close to the undercut, the stress field cannot be considered biaxial. Helped by Finite Element Modelling, we determined the stress tensor along the cantilever. The results show that, for a complete stress description of the cantilevers, it is necessary to take into account the role of diagonal and off-diagonal stress tensorial components.

Stress fields analysis in 3C-SiC free-standing microstructures by micro-Raman spectroscopy

Piluso N;Anzalone R;D'Arrigo G;La Via F
2013

Abstract

The study of the residual stress in the 3C-SiC/Si hetero-epitaxy is a crucial step for the development of SiC based sensors and microsystems. In this work, Raman microscopy is used to study the stress distribution on 3C-SiC cantilevers. The shift of transverse optical (TO) mode is linked to the stress fields present in the structures, whereas the full width at half maximum (FWHM) is an index of the lattice order. Micro-Raman map allows an accurate study of stress fields acting on the structure. Along the width of the cantilever, a trend of the TO Raman shift, moving towards higher frequency from the centre to the edges of the microstructure, has been observed. This is ascribed to etching processes removing some SiC portion at cantilever edges. Also, close to the anchorage zone, an undercut region is generated due to Silicon over-etch. The undercut region shows a worst lattice order (increased TO-FWHM) with respect to the unreleased and free standing regions. Close to the undercut, the stress field cannot be considered biaxial. Helped by Finite Element Modelling, we determined the stress tensor along the cantilever. The results show that, for a complete stress description of the cantilevers, it is necessary to take into account the role of diagonal and off-diagonal stress tensorial components.
2013
Istituto per la Microelettronica e Microsistemi - IMM
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.14243/215087
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