Edge direct tunneling current in nano‐scale MOSFET with high‐
Article publication date: 1 January 2008
Choosing suitable high‐K gate dielectrics to reduce the off‐state leakage (Ioff) by edge direct tunneling mechanism, demonstrating that the decreased Ioff increase significantly when the gate dielectrics permittivity are above 25. The purpose of this paper is to report that HfSiON and HfLaO are promising gate dielectrics.
The off‐state gate current, drain current, and substrate current are investigated. The Id‐Vgs characteristics for the 50 and 90 nm NMOSFET with various gate dielectrics are studied. Edge direct tunneling current (IEDT) with various gate dielectrics including SiO2, Si3N4 and HfO2 are compared and this paper also examines the IEDT with HfSiON and HfLaO gate dielectrics.
IEDT prevails over conventional gate‐induced drain‐leakage current (IGIDL), subthreshold leakage current (ISUB), band‐to‐band tunneling current (IBTBT) and it dominates off‐state leakage current. A large increase in off‐state leakage current occurs for smaller devices due to increase in IEDT at high Vdd. Although IEDT is decreased with increase in gate dielectrics permittivity K. The authors found fringing induced barrier lowering (FIBL) which could introduce significant off‐state leakage current for K>25. Fortunately, the IEDT with HfSiON and HfLaO gate dielectrics which are two‐five orders of magnitude lower than that of SiO2, furthermore, FIBL for HfSiON and HfLaO gate dielectrics are inconspicuous. Moreover, HfLaO and HfSiON have superior electrical performance and thermal stability.
Both edge direct tunneling and FIBL are considered to alternate high‐K gate dielectrics for nano‐scale MOSFET.
Yang, J., Li, G. and Liu, H. (2008), "Edge direct tunneling current in nano‐scale MOSFET with high‐
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