Analysis and optimisation of the hot-carrier degradation performance of 0.35-/spl mu/m fully overlapped LDD devices

The hot-carrier performance of a new type of fully overlapped device called FOND (Fully Overlapped Nitride-etch defined Device) is analysed and compared to the degradation behavior of conventional LDD devices that have similar initial electrical characteristics. It is shown that 0.35-/spl mu/m n-channel FOND devices can easily exceed the lifetime of the conventional LDD devices by two orders of magnitude. Based on experimental and simulation results, this increased hot-carrier resistance is explained by a smaller generation of damage and a lower sensitivity of the overlapped device to this damage. The decrease of the generation of the damage is the result of the lower lateral electric field due to the low n/sup -/-concentration and the overlap of the polysilicon gate on the n/sup -/-region while the significantly suppressed sensitivity is due to the complete overlap. Compared to LDD devices, the use of fully overlapped devices creates a wider process and reliability margin that can be used to optimise other electrical parameters.