This paper reports the shallow trench isolation (STI)-induced mechanical stress-related Kink effect behaviour of the 40 nm PD SOI NMOS device. As verified by the experimentally measured data and the 2D simulation results, the Kink effect behaviour in the saturation region occurs at a higher VD for the 40 nm PD device with a smaller S/D length (SA) of 0.17 mu m as compared to the one with the SA of 1.7 mu m due to the higher body-source bandgap narrowing (BGN) effect on the parasitic bipolar device (BJT) from the higher STI-induced mechanical stress, offset by the impact ionization (11) enhanced by the BGN in the high electric field region near the drain. (C) 2008 Elsevier Ltd. All rights reserved.