Analysis of Double Hump Substrate Current in NLDMOSFET

In this paper the phenomenon of Double Hump Substrate Current (DHSC) in NLDMOSFET is studied. We used 2-D device simulator MEDICI to investigate the physical mechanism. It is shown that the double hump substrate current is strongly dependent on the lateral electric field at the source-side. The fall-off in the substrate current at high V_GS is caused by hole velocity reduction due to the larger vertical electric field as V_GS increase. Besides, simulation result verifies that both of lower P-base implant and heavier NLDD doping concentration can help to eliminate the double hump substrate current effect because of reducing electric field in the source-side.