Model for the electric fields in LDD MOSFETs. II. Field distribution on the drain side

For pt.I see ibid., vol.36, no.2, p.375-81 (Feb. 1989). A self-consistent analytic model is proposed that accounts for the distribution of lateral and transversal electric fields of a MOSFET transistor on the drain side. It is shown in general that a lightly doped drain (LDD) MOSFET exhibits two field peaks on the drain side that are governed by different mechanisms. For moderate (realistic) subdiffusion lengths, the two peaks overlap and enhance each other. In the model the transversal field is treated on the same footing as the lateral field. It is shown that both fields are essential for explaining the behavior of substrate current, degradation phenomena, and spreading resistance. The model allows the extraction of simple formulas for analytic MOSFET models. The model predictions are corroborated by extensive simulations with MINIMOS 3 and LADIS simulators