Hot-carrier reliability in double-implanted lightly doped drain devices for advanced DRAMs

Hot-electron degradation in short-channel (0.50 mu m and 0.83 mu m) double-implanted lightly doped drain (DI-LDD) devices was characterised using DC stress tests. Compared to lightly doped drain (LDD) devices of the same effective channel length L_eff, the measurements indicate that channel hot-electron injection is more prevalent in devices with the p⁺-pocket implant due to a higher peak channel electric field. Degradation is more severe in both the drain current and transconductance. However, an improvement in short-channel effects was seen in DI-LDD devices over LDD devices. For the same L_eff, the punch-through voltage was higher and the subthreshold swing lower for the DI-LDD devices.