|
Abstract:
|
The Young’s modulus and Poisson’s ratio of high-quality silicon nitride films with 800 nm thickness,
grown on silicon substrates by low-pressure chemical vapor deposition, were determined by
measuring the dispersion of laser-induced surface acoustic waves. The Young’s modulus was also
measured by mechanical tuning of commercially available silicon nitride cantilevers, manufactured
from the same material, using the tapping mode of a scanning force microscope. For this
experiment, an expression for the oscillation frequencies of two-media beam systems is derived.
Both methods yield a Young’s modulus of 280–290 GPa for amorphous silicon nitride, which is
substantially higher than previously reported (E5146 GPa). For Poisson’s ratio, a value of n
50.20 was obtained. These values are relevant for the determination of the spring constant of the
cantilever and the effective tip–sample stiffness |