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Young's Modulus, Poisson's Ratio, and Nanoscale Deformation Fields of MEMS Materials

Published online by Cambridge University Press:  01 February 2011

I. Chasiotis ,
S. W. Cho ,
T. A. Friedmann  and
J. P. Sullivan
I. Chasiotis
Affiliation:
Mechanical and Aerospace Engineering andUniversity of Virginia, P.O. Box 400746 Charlottesville, Virginia 22904
S. W. Cho
Affiliation:
Materials Science and Engineering, University of Virginia, P.O. Box 400746 Charlottesville, Virginia 22904
T. A. Friedmann
Affiliation:
Sandia National Laboratories, Albuquerque, New Mexico 87185
J. P. Sullivan
Affiliation:
Sandia National Laboratories, Albuquerque, New Mexico 87185
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Abstract

The mechanical properties of hydrogen-free tetrahedral amorphous diamond-like carbon have been investigated in connection with its elastic and failure properties. Micro-tension specimens of gage thickness of 1.2–1.8 μm and widths of 10 μm or 50 μm have been fabricated by the Sandia National Laboratories (SNL). The mechanical characterization has been conducted via in situ AFM measurements and Digital Image Correlation (DIC) data strain analysis and the local deformation fields of (a) uniform and (b) internally notched tension specimens with acute notches (K=27) have been experimentally obtained. Young's modulus and Poisson's ratio were measured for the first time directly from such small specimens and averaged 750 GPa and v=0.16 respectively, while the tensile strength was found to be very consistent averaging 7.1 GPa. Stressed material domains with smaller dimensions in the vicinity of micronotches exhibited even higher failure strengths reaching 11.5 GPa with limited data scatter. AFM images of in situ tested specimens have indicated sp3 to sp2 phase transformations on the film surface that was subject to ultra-high tensile stresses (>6 GPa). This is the first time these phase transformations are observed during tensile tests of brittle materials.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 795: Symposium U – Thin Films - Stresses and Mechanical Properties X , 2003 , U10.9
Copyright
Copyright © Materials Research Society 2004

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References

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