Off-state leakage current in nano-scale MOSFET with Hf-based gate dielectrics

The off-state gate current, drain current and substrate current were simulated, exhibiting that the edge direct tunneling current (I
EDT
) from the gate overlap to the source and drain extension prevails over conventional gate induced drain leakage current (I
GIDL
), subthreshold leakage current (I
SUB
), band-to-band tunneling current (I
BTBT
) and I
EDT
dominates off-state leakage current. The I
d
-V
g
characteristics for the 50 and 90 nm MOSFETs were investigated, it was observed that a large increase in off-state leakage current (I
off
) occurs for smaller devices due to increase in edge direct tunneling current at high V
dd.
I
EDT
with various gate dielectrics including SiO
2
, Si
3
N
4
and HfO
2
were compared, which indicates that I
off
decreases because of reducing I
EDT
by increasing gate dielectrics permittivity % The I
d
-V
g
characteristics for various gate dielectrics were studied, we found that off-state leakage current arises because of fringing induced barrier lowering when K≫25. This paper also examined HfSiON and HfLaO gate dielectrics and the IEDT with them is 2–5 orders of magnitude lower than that of SiO
2
and FIBL is small. Moreover, HfLaO and HfSiON have superior thermal stability, they are promising gate dielectrics