ABSTRACT
With recent developments in and miniaturization of electronic de-
vices because of the increasing demand for high-density integration,
the size of elements has been approaching a few nanometers. In an
extreme, the atom-by-atom structure of atomic-scale elements, for
example, carbon nanotubes, comes in sight for future applications.
Industry has intensely developed devices on the micrometer scale
that havemultifarious functions-namely themicroelectromechani-
cal system (MEMS) and the nano-electromechanical system (NEMS),
including small sensors and actuators. The stress applied to a
nanocomponent stems from various sources, such as mechanical
loading (e.g., polishing), residual stress, and thermal elongation
mismatch in processing as well as service. Hence, to ensure
reliability, nanocomponents should be carefully designed on the
basis of mechanical conditions. Because they are composed of
various materials with different nanosize geometries, the stress
concentration originating from their shapes plays a critical role
in the fracture mechanisms of nanocomponents. Moreover, to
realize high-density integration of the components in devices,
small materials with different mechanical properties (e.g., elastic
modulus) are adhered to each other without an interlayer or with
an ultrathin one. Since the mismatch of deformation often brings
about inner stress, its interface is the most critical site in terms of
fracture.
