Characterization of Impact of Vertical Stress on FinFETs

We investigated the vertical stress impact on FinFETs using in-situ electrical measurements in a nano-indenter setup. We found that the impact of vertical stress on I
d
for N and P-type FinFETs increases for longer gate lengths. According to mechanical simulations, if vertical stress is applied to the sample surface, the FinFET feels not only vertical compressive stress but also non-negligible horizontal compressive stress. Furthermore, we confirmed that the in-plane compressive stresses have different values in directions perpendicular and parallel to the Fin using S-Device simulation. The experimental results of I
d
variations can be explained by a change of electron (hole) effective mass and electron scattering considering the vertical and horizontal piezo resistivity coefficients.