What question did this study set out to answer?

Determine whether the elastic modulus and fracture strength of polysilicon thin films depend on specimen dimensions and microstructural variation.

January 1, 2001Journal of Microelectromechanical Systems

Effect of specimen size on Young's modulus and fracture strength of polysilicon

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Authors

WSW. N. SharpeJohns Hopkins University KJKamili M. JacksonFlex (United States)KHKevin J. HemkerJohns Hopkins University

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Implication

Mechanical testing demonstrates invariant Young's modulus but increased fracture strength in smaller polysilicon specimens, indicating that surface flaws govern size-dependent brittle failure.

Key Points

Determine whether the elastic modulus and fracture strength of polysilicon thin films depend on specimen dimensions and microstructural variation.
Conducted tensile tests and transmission electron microscopy on polysilicon specimens across varying thicknesses (1.5 to 3.5 µm), widths (6 to 600 µm), and lengths (250 to 4000 µm) from a standardized fabrication run.
Evaluated grain structure, dimensional deviations from mask designs, and Young's modulus using three independent measurement approaches.
Young's modulus measured 158 ± 10 GPa across all three measurement approaches, showing no substantial dependence on specimen size or thickness.
Fracture strength increased from 1.21 ± 0.08 GPa to 1.65 ± 0.28 GPa as total surface area decreased, attributable to a lower prevalence of surface flaws in smaller specimens.
Transmission electron microscopy confirmed uniform, fine columnar grains (0.2–0.5 µm) across all sizes, indicating that specimen geometry does not alter internal microstructure.

Cite This Study

Sharpe et al. (2001) studied this question.

synapsesocial.com/papers/6a8a943c755d28965dfd73e3 https://doi.org/10.1109/84.946774

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Implication

Mechanical testing demonstrates invariant Young's modulus but increased fracture strength in smaller polysilicon specimens, indicating that surface flaws govern size-dependent brittle failure.

Effect of specimen size on Young's modulus and fracture strength of polysilicon

Discussion

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Implication

Key Points

Cite This Study

Effect of specimen size on Young's modulus and fracture strength of polysilicon

Discussion

Member takes

Implication

Key Points

Cite This Study

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