The strong electric field across the pinched-off channel of a saturated MOS transistor causes hot carrier degradation. The electric field intensity diminishes if the depletion region can somewhat be widened. In a conventional transistor, the depletion region cannot intrude to any significant extent into the heavily doped drain. If the drain diffusion is more lightly doped, then the depletion region can extend into the drain as well as into the channel and the electric field intensity will decrease. Such lightly doped drain(LDD) transistors can withstand substantially higher drain-to-source voltages than can conventional single doped drain(SDD) devices