In situ MEMS testing: correlation of high-resolution X-ray diffraction with mechanical experiments and finite element analysis

Abstract

New methods are needed in microsystems technology for evaluating microelectromechanical systems (MEMS) because of their reduced size. The assessment and characterization of mechanical and structural relations of MEMS are essential to assure the long-term functioning of devices, and have a significant impact on design and fabrication.Within this study a concept for the investigation of mechanically loaded MEMS materials on an atomic level is introduced, combining high-resolution X-ray diffraction (HRXRD) measurements with finite element analysis (FEA) and mechanical testing. In situ HRXRD measurements were performed on tensile loaded single crystal silicon (SCSi) specimens by means of profile scans and reciprocal space mapping (RSM) on symmetrical (004) and (440) reflections. A comprehensive evaluation of the rather complex XRD patterns and features was enabled by the correlation of measured with simulated, ‘theoretical’ patterns. Latter were calculated by a specifically developed, simple and fast approach on the basis of continuum mechanical relations. Qualitative and quantitative analysis confirmed the admissibility and accuracy of the presented method. In this context [001] Poisson’s ratio was determined providing an error of less than 1.5% with respect to analytical prediction. Consequently, the introduced procedure contributes to further going investigations of weak scattering being related to strain and defects in crystalline structures and therefore supports investigations on materials and devices failure mechanisms.

Lattice Strain and Defects Analysis in Nanostructured Semiconductor Materials and Devices by High‐Resolution X‐Ray Diffraction: Theoretical and Practical Aspects

“…The features in the maps (Figure 9) indicate the presence of two regions differently strained, and parallel oriented with an appreciable inclination, especially in the mid-part of the sample. [12] With the increase of the applied tensile force, the separation of the two regions becomes more evident which clearly indicates a combined presence of lattice strain and tilt. Furthermore, the authors have coupled HRXRD measurements with finite element (FE) simulations for both mechanical behavior and multidimensional pattern reconstruction in order to provide a better understanding of the microwire behavior under load, which is essential for micro electro-mechanical systems (MEMS) operation.…”

“…[5][6][7][8][9] Their presence and mobility decrease the performance and favor failure after a certain period of application. [10][11][12][13] Epitaxial growth of semiconductor materials is a well-established manufacturing method, but it is also well known for introducing edge misfit and screw threading dislocations. [14][15][16] Processes such as, wafer bonding, [17] chemical etching, and e-beam lithography, [18] can also have detrimental effects on the crystal structure of semiconductor materials.…”

“…Reproduced under terms of the CC-BY license. [12] Copyright 2017, the Authors. Published by IOP Publishing.…”

Real- and Q-space travelling: multi-dimensional distribution maps of crystal-lattice strain (ɛ044) and tilt of suspended monolithic silicon nanowire structures

“…Further details regarding the fabrication process are explained elsewhere (Tasdemir et al, 2016(Tasdemir et al, , 2018. Although the bulk-scale (millimetre-and even micrometre-scale) properties of silicon have been studied in great detail (Gaither et al, 2010(Gaither et al, , 2011Schifferle et al, 2017), the nanoscale properties of silicon still remain an interesting matter of investigation. Here, we focus on the identification of the nanometre-scale intrinsic properties of silicon, possibly coming from the fabrication processes, using high-resolution X-ray diffraction.…”

“…Reduced lifetime and limited reliability are affected by prestrains and damage introduced by large loads during device manufacture or operation that exceed the critical strength (Dommann et al, 2003;Neels, Niedermann & Dommann, 2008). Furthermore, typical manufacturing process steps, such as electron-beam lithography, deep reactive ion etching (DRIE), thermal annealing, dicing and bonding, could favour failure as well (Schifferle et al, 2017). In addition, such critical steps have a direct impact on the mechanical properties, therefore reducing significantly the lifetime of such devices (Jadaan et al, 2003).…”