The impact of shallow trench isolation effects on circuit performance

In nanometer technologies, shallow trench isolation (STI) induces thermal residual stress in active silicon due to post-manufacturing thermal mismatch. The amount of STI around an active region depends on the layout of the design, and the biaxial stress due to STI results in placement-dependent variations in the the transistor mobilities and threshold voltages of the active devices. An analytical model based on inclusion theory in micromechanics is employed to accurately estimate the stresses and the strains induced in the active region by the surrounding STI in the layout. The induced changes in mobility and threshold voltage changes are computed at the transistor level, and then propagated to the gate and circuit levels to predict circuit-level delay and leakage power for a given placement.