Residual Stress Measurement on a MEMS Structure With High-Spatial Resolution

Abstract

Abstract-A new approach to the local measurement of residual stress in microstructures is described in this paper. The presented technique takes advantage of the combined milling-imaging features of a focused ion beam (FIB) equipment to scale down the widely known hole drilling method. This method consists of drilling a small hole in a solid with inherent residual stresses and measuring the strains/displacements caused by the local stress release, that takes place around the hole. In the presented case, the displacements caused by the milling are determined by applying digital image correlation (DIC) techniques to high resolution micrographs taken before and after the milling process. The residual stress value is then obtained by fitting the measured displacements to the analytical solution of the displacement fields. The feasibility of this approach has been demonstrated on a micromachined silicon nitride membrane showing that this method has high potential for applications in the field of mechanical characterization of micro/nanoelectromechanical systems.[1634]

Statistical analysis of SEM image noise

“…Different surface decoration techniques have been found in literature depending on the studied surface area and the homogeneity of the decoration (pattern) [11]. Deposition of yttria-stabilizedzirconia (YSZ) nanoparticles is a good method because it can be applied rapidly on large surface areas [9]. Therefore, YSZ nanoparticles were deposited on the surface from a 40% aqueous ethanol suspension (~30 mg/cm 3 ) and dried at room temperature before the measurements.…”

“…Several authors [8][9][10] have previously used SEM image correlation to measure stresses on the top of a coating by relaxation displacement measurement after FIB milling. DIC is an image-based method that consists in dividing the images to be compared in smaller sub-regions, called 'facets' [6].…”

Magnetic Field Sensors Based on Microelectromechanical Systems (MEMS) Technology

“…For example thermal stresses inside resonant devices (Hull, 1999) causes strains in the structures which in turn involve (Sabaté et al, 2007) The fabrication process is based on bulk micromachining technology on (100) 4" silicon-oninsulator (SOI) wafers. The process starts by growing a thin thermal oxide layer and depositing a silicon nitride layer on a SOI n-type substrate.…”

Residual Stress Measurement in Micro-region Using Digital Image Correlation Method

“…To better understand the generation of residual stress so as to effectively control the magnitude of residual stress, the techniques to measure residual stress need to be developed for film-matrix structures. At present, the existing measurement techniques mainly include X-ray diffraction [1,2], Raman spectroscopy [3,4] and measuring by the release of residual stress [5][6][7][8][9][10][11][12]. For the former two methods, only the average residual stress within the measured area can be obtained.…”

“…Sabate et al [5][6][7] used FIB to fabricate a hole or a slot at the film surface to release the residual stress and utilized digital image correlation (DIC) to measure residual stress in a film. Massl et al [8] used FIB to process micro cantilever and measured its deflection by DIC to obtain the residual stress of a film.…”