A subthreshold surface potential modeling of drain/source edge effect in MOS transistors

An analytical subthreshold surface potential in an short-channel MOS transistor, incorporating the fringing fields at the two ends of the device, is proposed. For short channel devices, the effect of the source and drain edge electric fields around the source and drain junctions on the surface potential is very important. In this model we included this edge electric field. This gives a more accurate prediction of the surface potential for the small dimensional MOS transistors. A pseudo-2D analysis applying Gauss´ law on the surface is used to model both the vertical and horizontal fields. 2-D numerical device simulator DESSIS of ISE TCAD is used to verify the improvement of our model among the surface potential profile.