The effects of STI induced mechanical strain on GIDL current in Hf-based and SiON MOSFETs

Abstract

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 (nMOSFETs) 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 HfO 2 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.