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Microscale Measurement of Stresses in a Silicon Flexure Using Raman Spectroscopy

Published online by Cambridge University Press:  11 February 2011

V. T. Srikar ,
A. K. Swan ,
B.B. Goldberg ,
M. S. Ünlü  and
S. M. Spearing
V. T. Srikar
Affiliation:
Massachusetts Institute of Technology, Cambridge, MA 02139, U.S.A. (vts@alum.mit.edu)
A. K. Swan
Affiliation:
Boston University, Boston, MA 02215, U.S.A.
B.B. Goldberg
Affiliation:
Boston University, Boston, MA 02215, U.S.A.
M. S. Ünlü
Affiliation:
Boston University, Boston, MA 02215, U.S.A.
S. M. Spearing
Affiliation:
Massachusetts Institute of Technology, Cambridge, MA 02139, U.S.A. (vts@alum.mit.edu)
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Abstract

We report the use of Raman spectroscopy to characterize the bending stresses in a deep reactive-ion etched, single-crystal, silicon flexure of length 2950 μm, width 480 μm, thickness 150 μm, and fillet radius 65 μm, subjected to a tip displacement of 69.5 μm. The spectral resolution of the measurement was 0.02 cm-1, which corresponds to a stress resolution of ∼10 MPa, and the spatial resolution was ∼1 μm. Line scans were performed across the thickness, at several locations along the length, of the flexure. The changes in the Raman shift were converted to stress values, assuming a uniaxial stress state, without the use of any fitting parameters. A comparison of the measured values with the predictions of analytical and numerical models indicates agreement to within 25–35 MPa (or ∼15%) at locations sufficiently distant from the root. At the root itself, the complex nature of the stress distribution precludes unambiguous stress determination using spectroscopic measurements.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 741: Symposium J – Nano- and Microelectromechanical Systems (NEMS and MEMS) and Molecular Machines , 2002 , J9.5
Copyright
Copyright © Materials Research Society 2003

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References

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