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FIB based Measurements for Material Characterization on MEMS Structures

 
: Vogel, D.; Lieske, D.; Gollhardt, A.; Keller, J.; Sabaté, N.; Morante, J.R.; Michel, B.

:

Geer, R.E. ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
Testing, reliability, and application of micro- and nano-material systems III : Proceedings of the Third Conference on Testing, Reliability, and Application of Micro- and Nano-Material Systems; 8 - 10 March 2005, San Diego, California, USA
Bellingham/Wash.: SPIE, 2005 (SPIE Proceedings Series 5766)
ISBN: 0-8194-5747-7
pp.60-69
Conference on Testing, Reliability, and Application of Micro- and Nano-Material Systems <3, 2005, San Diego/Calif.>
English
Conference Paper
Fraunhofer IZM ()

Abstract
Design, manufacturing and packaging of new MEMS/NEMS devices demands detailed know-how on mechanical material properties used. Because of size effects due to miniaturization as well as manufacturing and exploitation influences on material properties, classical methods of material testing often do not provide correct material data. Values published by different authors and determined on various devices can differ by ,e.g., a factor of three and more for the same material. Consequently, a strong need exists to measure material properties directly on MEMS devices or MEMS precursor structures. -- Respectively, the authors present a new approach, fibDAC, which allows to measure and analyze deformation fields on stressed micro and nano components, which can be utilized for mechanical material haracterization. The method bases on digital image correlation algorithms (DIC) applied locally to load state images captured in focused ion beam (fib) equipment. As a result, deformation fields are determined, which occur due to loading of MEMS structures inside the FIB station. Combining measured fields with finite element simulations relevant mechanical material properties can be evaluated. Corresponding object loading is accomplished either externally by testing modules designed for application inside the FIB equipment or by FIB specimen treatment in order to release inherent specimen stresses. A similar tool, called microDAC/nanoDAC, has been reported earlier [1,2] and applies DIC techniques to SEM or AFM images. The advantages of the new fibDAC approach occur in the incorporation of specimen preparation (ion milling, ion beam surface polishing and DIC patterning), specimen loading by ion milling and DIC deformation measurement in a single equipment. -- The authors present several applications of fibDAC measurements on stressed micro components. Emphasis is made to the evaluation of residual stresses on micro component structures. "Smart" ion milling is used to cause local deformations resulting from inherent residual stresses. Their analysis gives access to quantified residual stresses. Although being not completely nondestructive the method possesses advantages against other approaches, like e.g. built-in stress sensing structures, because of its more general suitability with regard to quite different structures and residual stress states.

: http://publica.fraunhofer.de/documents/N-120472.html