Effects of uniaxial mechanical stress on drive current of 0.13 μm MOSFETs

We study the effects of both external mechanical stress and intrinsic stress due to trench isolation on drive currents of 0.13 μm-node MOSFETs. The drive current, I_dsat, of PMOS is enhanced by about 13% while that of NMOS is reduced by about 9% upon applying a uniaxial compressive stress along the channel of L_physical=85 nm. The shifts in linear drive current, I_dlin, are larger. By applying the external stress, we have simultaneously reproduced, for both PMOS and NMOS, the I_dsat and I_dlin shifts due to different gate-trench-isolation distances. We find that the shifts by the applied stress, ΔI_dsat/I_dsat0 and ΔI_dlin/I_dlin0, decrease with decreasing gate length. The change in total resistance, Δ(V_ds/I_dlin), is a linear function of gate length. Because of the mobility dependence on external stress, we have also been able to extract source-drain series resistance, R_sd, by simply bending the wafer.