Micro-Raman analysis of a micromachined 3C-SiC cantilever N. Piluso 1 , R. Anzalone 1 , M. Camarda 1 , A. Severino 1 , G. D’Arrigo 1 , A. La Magna, F. La Via 1 1 Istituto per la Microelettronica e Microsistemi IMM-CNR, sezione di Catania, Stradale Primosole 50, 95121, Catania, Italy Corresponding author: nicolo.piluso@imm.cnr.it Keywords: micro-Raman, stress relaxation, microstructures, Finite element modeling Abstract. In this work, Raman microscopy is used to study the stress distribution in a 3C-SiC cantilever. Also, a comparison between the strain distribution observed on the microstructure, using the shift of transverse optical mode in micro-Raman maps, with the values predicted using a recent analytic theory [1] has been done. Along the width of the cantilever is observed a reduction of stress ascribed to the etching processes that removes a thin layer of the interface between the 3C-SiC film and the substrate close to the edge of the microstructure. It is possible to show that this variation can be ascribed to a non-linearity of the strain field along the 3C-SiC film thickness. Also, helped by Finite Element Modeling, we determined the stress tensor along the cantilever. This result shows 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. Introduction The study of stress in 3C-SiC free standing structure, such as a cantilever, represents a crucial step in order to optimize the manufacturing processes for Micro Electro-Mechanical Systems (MEMS) [2]. Hetero-epitaxy of 3C-SiC on Si substrates is still affected by a low crystalline quality of the epilayer and by the bending of the entire wafer processed. Defects, together with the SiC/Si interface, generate a stress field into the hetero-epitaxial system. The residual stress is strongly affected by deposition conditions and subsequent fabrication processes. Stress measurement techniques, such as micro-Raman microscopy, are essential for both process development and process monitoring. A spatially resolved stress map (with a lateral resolution of 1 μm) on a micro-machined freestanding cantilever is obtainable by using back scattering Raman microscopy, a not destructive technique particularly useful for study of the local stress in micro-structures with the diameter of the laser spot less than 2 μm. This spot size allows an acquisition of Raman spectra with a sufficiently high spatial resolution, ensuring a local analysis and a study of the distribution of the stress field in comparison with the morphology of the structure. Experimental Details We collected Raman spectra using a HR800 integrated system by Horiba Jobin Yvon in a back- scattering configuration with a microscope coupled confocally to a 800 mm focal length spectrograph and a grating with 2400gr/mm. The excitation wavelength is supplied by a He-Ne laser (632.8 nm) that was focussed on the sample by a x100 objective with numerical aperture (NA) of 0.95. The power of the laser is 20mW and no heat effect during the measurements was observed. This is mainly due to the transparency of the film at the wavelength of the laser. The mean thickness of the epitaxial layers is about 3 μm, thus we probe the entire layer, since the 3C-SiC band gap is higher (about 520nm) than the laser excitation photon energy. The typical Raman signal of a 3C-SiC monocrystal epitaxial film consists of transverse (TO) and longitudinal (LO) optical phonon mode. We analyzed the TO mode because it is not affected by doping (in this case unintentionally doping) and it is suitable to probe the order of the crystal lattice, as well as its stress field. A shift of the TO Raman peak indicates the presence of stress in the film mainly due to the Materials Science Forum Vols. 717-720 (2012) pp 525-528 Online available since 2012/May/14 at www.scientific.net © (2012) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/MSF.717-720.525 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 88.39.221.60-06/06/12,13:27:23)