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Fracture Strength of Polycrystalline Silicon

Published online by Cambridge University Press:  10 February 2011

P.T. Jonestt,
G.C. Johnsontt and
R.T. Howe
P.T. Jonestt
Affiliation:
Berkeley Sensor & Actuator Center, University of California, Berkeley, CA 94720Department of Mechanical Engineering, University of California, Berkeley, CA 94720
G.C. Johnsontt
Affiliation:
Berkeley Sensor & Actuator Center, University of California, Berkeley, CA 94720Department of Mechanical Engineering, University of California, Berkeley, CA 94720
R.T. Howe
Affiliation:
Berkeley Sensor & Actuator Center, University of California, Berkeley, CA 94720Department of Mechanical Engineering, University of California, Berkeley, CA 94720Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, CA 94720
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Abstract

A structure has been developed to measure the fracture strength of thin films that allows for a large amount of statistical data to be generated from a single die. The strength of a material is determined by measuring the displacement at fracture of cantilever beams bending in-plane. This device has been used to measure the fracture strain of three different polysilicon materials: polysilicon from two different MCNC MUMPS runs and a polysilicon fabricated at the Microfabrication Laboratory at the University of California at Berkeley. The strain at fracture of the MUMPS polysilicon was measured to be 1.5% ± 0.2% for both MCNC MUMPS runs. The Berkeley polysilicon exhibited a fracture strength of 1.2% ± 0.1%, a difference from the MUMPS result that is statistically significant. Also, no statistical difference in fracture strength was measured on specimens that were super-critically carbon dioxide dried as opposed to furnace dried. In a separate experiment, the Young's modulus of the MCNC MUMPS polysilicon was found to be 173 ± 20 GPa.

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References

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