Stress Analysis in a Si1-xGex-Channel-Transistor by Scanning Moiré Fringe Imaging

We report on quantitative strain measurement of a Si
_1−x
Ge
_x
-channel-transistor performed using the scanning moiré fringes that appear in high-angle annular dark-field scanning transmission electron microscopy. The strain fields in the Si
_1−x
Ge
_x
-channel region were measured along three orthogonal axes (
X
,
Y
, and
Z
). This three-axis strain measurement enabled us to calculate the stress applied in the channel region of the transistor, which was
\(\sigma _{xx}=-4.3\)
GPa,
\(\sigma _{yy}=-2.8\)
GPa, and
\(\sigma _{zz}=- 1.5\)
GPa for the longitudinal, transverse, and vertical directions relative to the current flow, respectively. The three-axis stress analysis demonstrated in this letter will enable comprehensive understanding of the strain engineering in electronic devices.