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Proceedings Paper

Inspection system for MEMS characterization on wafer level using ESPI
Author(s): Petra Aswendt; Claus-Dieter Schmidt; Dirk Zielke; Steffen Schubert
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Paper Abstract

Characterizing the mechanical properties of MEMS structures at a very early stage of manufacturing is a challenging task for quality assurance in this field. The paper describes a new solution that is based upon the vibration analysis of the microparts. The microvibrations have nm amplitudes and are detected by electronic speckle pattern interferometry (ESPI). A specific signal processing technique (moving phase reversal reference) has been applied to make the solution robust. Comprehensive numerical simulations provide the theoretical base for estimating the frequencies and mode shapes expected for perfect MEMS as well as for typical faults. The complete wafer ensemble was modeled to gain knowledge about best suited wafer clamping and about interactions between the microparts vibrating. A laboratory system for 4' wafer has been built, and extensive tests show that such key properties as e.g. the thickness of springs or membranes can be determined exactly by means of the hybride approach. Automated frequency scanning and corresponding digital image processing open the way to reliable and fast industrial systems for MEMS testing on wafer level.

Paper Details

Date Published: 23 October 2001
PDF: 8 pages
Proc. SPIE 4400, Microsystems Engineering: Metrology and Inspection, (23 October 2001); doi: 10.1117/12.445604
Show Author Affiliations
Petra Aswendt, Fraunhofer-Institut fuer Werkzeugmaschinen und Umformtechnik (Germany)
Claus-Dieter Schmidt, Fraunhofer-Institut fuer Werkzeugmaschinen und Umformtechnik (Germany)
Dirk Zielke, GEMAC mbH (Germany)
Steffen Schubert, GEMAC mbH (Germany)

Published in SPIE Proceedings Vol. 4400:
Microsystems Engineering: Metrology and Inspection
Christophe Gorecki; Werner P. O. Jueptner; Malgorzata Kujawinska, Editor(s)

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