The effects of shallow trench isolation (STI) induced mechanical strain on gate induced drain leakage (GIDL) current in Hf-based and SiON n-type metal oxide semiconductor field effect transistors (nMOS-FETs) are investigated in detail. With T-CAD simulator, the compressive strain is found to increase with decreasing active area length. The STI-induced mechanical strain induces band narrowing and increases intrinsic carrier concentration, thus enhancing GIDL current via both trap-assisted tunneling and band-to-band tunneling. In addition, the HfO2 gated nMOSFET has higher strain sensitivity than that of the SiON gated device for the higher density of interface states induced by the mechanical strain. Finally, the symmetric layout shows a higher ability to suppress the STI-enhanced GIDL current with the same active area length. (C) 2009 Elsevier Ltd. All rights reserved.