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

We report on quantitative strain measurement of a Si_1-xGe_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 Si1-xGex-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 σ_xx = -4.3 GPa, σ_yy = -2.8 GPa, and σ_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.